Wyniki wyszukiwania - BazTech

1

Determination of borides in Fe-Mo-B sintered powders using diffraction methods

Karwan-Baczewska J., Perek-Nowak M., Majchrowska M., Garbacz-Klempka A.

Archives of Materials Science and Engineering

|

2024

|

Vol. 127, nr 1

5--11

EN

Purpose: Modification of sintered iron with the addition of molybdenum and boron leads to the formation of boride phases that significantly impact the properties of the sintered materials. The paper aims to determine Fe-Mo-B phases that might be formed during the sintering of base powders. With EDS microanalysis, determining those phases in the microstructure is difficult since the B-Kα peak is extremely close to Mo-Mζ (only a 9.3 eV difference). Thus, diffraction techniques must be implemented to unambiguously define the phases occurring in the sintered samples (WDS and EBSD). Design/methodology/approach: The sintered samples were obtained from initial powders of Fe, Mo, and B that were mixed and compressed. The reducing hydrogen atmosphere was used to sinter green samples at 1200°C for 60 minutes. The obtained sinters were subjected to microstructural observations by scanning electron microscope, and some analyses (EDS/WDS and EBSD) were conducted, which led to the determination of phases present in the material. Findings: Based on the investigations conducted, iron, molybdenum, and molybdenum-iron borides have been reported. It is confirmed with the EBSD method that Fe2B, MoB and FeMo2B2 phases are formed in particles’ connection regions. Besides, the interparticle region, formed due to a liquid phase during sintering, is based on Fe-Fe2B eutectic. The microstructural observations prove that the amount of the liquid phase, and thus the size of the interparticle region, diminishes with increasing molybdenum content. It was also noted that the iron matrix (interior of former iron particles) is free from contributing elements coming from boron or molybdenum powders. Research limitations/implications: The application of the EDS method is limited in the case of measuring boron in Mo-containing alloys and phases. The EDS method does not have a sufficient energetic resolution to separate the B-Kα line from Mo-Mζ one. Thus, it must be complemented with WDS and EBSD in order to unambiguously determine the presence and localization of iron and molybdenum borides. Practical implications: It can be stated that WDS has sufficient energy resolution to separate B-Kα from Mo-Mζ emission lines. Therefore, WDS analysis is suitable for boride observation in sintered iron powders by constructing distribution maps of interparticle connection regions and precipitates. Besides, measurements by the EBSD method can be used to confirm the presence of Fe2B, MoB and FeMo2B2 phases. Originality/value: Determination of boron-containing phases in Fe-Mo-B sinters by means of diffraction methods.

2

Influence of Modification in Centrifugal Casting on Microstructure and Mechanical Properties of Silicon Bronzes

Garbacz-Klempka A., Kozana J., Piękoś M., Papaj P., Papaj P., Perek-Nowak M.

Archives of Foundry Engineering

|

2018

|

Vol. 18, iss. 3

11--18

EN

Silicon bronzes are characterised by good mechanical properties and by high corrosion and mechanical wear resistance. The process of sleeve casting by means of the centrifugal casting with the horizontal axis of the mould rotation was analysed. The assessment of the influence of modification and centrifugal casting parameters on the microstructure and mechanical properties of alloys was carried out in the hereby work. Zirconium was applied as a modifier. Speed of rotation of the mould was the variable parameter of the centrifugal casting. The investigation results were summarised on the basis of the microstructure analysis and mechanical properties determination: UTS, proof stress, A10 and BHN. The experiment aimed at finding the information in which way the modification together with changing the pouring parameters influence the mechanical properties of the CuSi3Zn3FeMn alloy.

3

Assessment of Impact of Nickel Additions on Tin Bronzes

Kozana J., Garbacz-Klempka A., Piękoś M., Czekaj J., Perek-Nowak M.

Archives of Foundry Engineering

|

2018

|

Vol. 18, iss. 1

53--60

EN

High prices of tin and its limited resources, as well as several valuable properties characterising Cu-Sn alloys, cause searching for materials of similar or better properties at lower production costs. The influence of various nickel additions to CuSn10 casting bronze and to CuSn8 bronze of a decreased tin content was tested. Investigations comprised melting processes and casting of tin bronzes containing various nickel additions (up to 5%). The applied variable conditions of solidification and cooling of castings (metal and ceramic moulds) allowed to assess these alloys sensitivity in forming macro and microstructures. In order to determine the direction of changes in the analysed Cu-Sn-Ni alloys, the metallographic and strength tests were performed. In addition, the solidification character was analysed on the basis of the thermal analysis tests. The obtained results indicated the influence of nickel in the solidification and cooling ways of the analysed alloys (significantly increased temperatures of the solidification beginning along with increased nickel fractions in Cu-Sn alloys) as well as in the microstructure pattern (clearly visible grain size changes). The hardness and tensile strength values were also changed. It was found, that decreasing of the tin content in the analysed bronzes to which approximately 3% of nickel was added, was possible, while maintaining the same ultimate tensile strength (UTS) and hardness (HB) and improved plasticity (A5).

4

Analysis of a Castings Quality and Metalworking Technology. Treasure of the Bronze Age Axes

Garbacz-Klempka A., Kaczmarek Ł., Kwak Z., Kozana J., Piękoś M., Perek-Nowak M., Długosz P.

Archives of Foundry Engineering

|

2018

|

Vol. 18, iss. 3

179--285

EN

Cast axes are one of the most numerous categories of bronze products from earlier phases of the Bronze Age found in Poland. They had multiple applications since they were not only used objects such as tools or weapons but also played the prestigious and cult roles. Investigations of the selected axes from the bronze products treasure of the Bronze Age, found in the territory of Poland, are presented in the hereby paper. The holder of these findings is the State Archaeological Museum in Warsaw. Metallurgical investigations of axes with bushing were performed in respect of the casting technology and quality of obtained castings. Macroscopic observations allowed to document the remains of the gating system and to assess the range and kind of casting defects. Light microscopy revealed the microstructure character of these relicts. The chemical composition was determined by means of the X-ray fluorescence method with energy dispersion (ED-XRF) and by the scanning electron microscopy with X-ray energy dispersion analysis in micro-areas (SEM-EDS). The shape and dimensions of cores, reproducing inner parts of axes were identified on the basis of the X-ray tomography images. Studies reconstructed production technology of the mould with gating system, determined chemical composition of the applied alloys and casting structures as well as revealed the casting defects being the result of construction and usage of moulds and cores.

5

Elastic properties and structural observations of Distaloy SA powder sintered with boron and carbon

Perek-Nowak M., Karwan-Baczewska J.

Metallurgy and Foundry Engineering

|

2017

|

Vol. 43, no. 2

107--115

EN

One of the methods aimed at increasing the density in PM parts is the process of activated sintering performed by adding boron as elementary boron powder, for example. Under this researchwork novel, PM materials were obtained based on prealloyed and diffusion bonded powder (type: Distaloy SA) with the following chemical composition: Fe-1.75%Ni-1.5%Cu-0.5%Mo, with the addition of 0.55 wt.% carbon and boron (0.2, 0.4 and 0.6 wt.%). Distaloy SA samples alloyed with carbon and boron were manufactured by mixing the powders in a Turbula mixer, then compacting the mixture in a hydraulic press under a pressure of 600 MPa and sintered in a tube furnace at 1473 K for 60 minutes in a hydrogen atmosphere. The densification process of Distaloy SA parts with boron and carbon depends on the sintering mechanism. In order to evaluate the sintering mechanism of the PM samples, structural investigations using SEM/EDS were performed. During sintering of these materials at 1473 K, a liquid phase is generated as a result of the reaction occurring between the alloy matrix and the complex of carbo-borides, which leads to a considerable degree of consolidation. The elastic properties of the sintered samples (such as Young’s modulus and the damping coefficient) were measured in a tensile test with a Förster elastometer.

PL

Jedną z metod mających na celu zwiększenie gęstości części PM jest proces aktywnego spiekania, zachodzący np. w wyniku dodania boru w formie elementarnego proszku boru. W badaniach omawianych w niniejszym artykule nowoczesne materiały PM zostały uzyskane ze stopowanych i dyfuzyjnie związanych proszków Distaloy SA o składzie Fe-1,75%Ni-1,5%Cu-0,5%Mo z dodatkiem 0,55% wag. węgla i boru (0,2, 0,4 i 0,6% wag.). Próbki Distaloy SA stopowane węglem i borem otrzymano w wyniku mieszania proszków w mieszalniku Turbula, a następnie zagęszczenia na prasie hydraulicznej pod ciśnieniem 600 MPa i spiekania w piecu rurowym w temperaturze 1473 K w atmosferze wodoru przez 60 min. Zagęszczanie części ze stopu Distaloy SA z borem i węglem zależy od mechanizmu spiekania. W celu określenia mechanizmu spiekania próbek PM dokonano obserwacji strukturalnych za pomocą SEM z przystawką EDS. Podczas spiekania omawianych materiałów w temperaturze 1473 K w wyniku reakcji pomiędzy osnową a złożonymi węglano-borkami tworzy się ciekła faza, która prowadzi do znacznej konsolidacji. Własności mechaniczne spiekanych próbek takie jak moduł Younga czy współczynnik tłumienia zostały zmierzone w próbie rozciągania i na elastometrze Förstera.

6

Bronze Jewellery from the Early Iron Age urn-field in Mała Kępa. An approach to casting technology

Garbacz-Klempka A., Kowalski Ł., Gackowski J., Perek-Nowak M.

Archives of Foundry Engineering

|

2017

|

Vol. 17, iss. 3

175--183

EN

This study characterizes the bronze jewellery recovered from the Lusatian culture urn-field in Mała Kępa (Chełmno land, Poland). Among many common ornaments (e.g. necklaces, rings, pins) the ones giving evidence of a steppe-styled inspiration (nail earrings) were also identified. With the dendritic microstructures revealed, the nail earrings prove the implementing of a lost-wax casting method, whereas some of the castings were further subjected to metalworking. The elemental composition indicates the application of two main types of bronze alloys: Cu-Sn and Cu-Sn-Pb. It has been established that the Lusatian metalworkers were familiar with re-melting the scrap bronze and made themselves capable of roasting the sulphide-rich ores. The collection from Mała Kępa has been described in terms of its structure and composition. The investigations were made by means of the energy dispersive X-ray fluorescence spectroscopy (ED-XRF), scanning electron microscopy (SEM) coupled with an energy dispersive X - ray analysis system (EDS) and optical microscopy (OM). In order to fingerprint an alloy profile of the castings with a special emphasis on the nail earrings, the data-set (ED-XRF, EDS) was statistically evaluated using multidimensional analyses (FA, DA).

7

Microstructure of selected 7xxx series aluminum alloys obtained by semi-continuous casting

Kwak Z., Garbacz-Klempka A., Perek-Nowak M.

Prace Instytutu Odlewnictwa

|

2016

|

Vol. 56, no. 3

221--232

EN

The study was conducted for two selected 7xxx series aluminum alloys according to PN-EN 573-3:2010 – Polish version. The analysis of ingots was carried out on 7003, 7003S and 7010, 7010K alloys with a similar ratio of zirconium content. Symbols S and K are our internal modifications, still compatible with the standard. The ingots were made by semi-continuous casting. Aluminum alloys of this series, with improved properties, are intended for plastic-processing. The aim of this publication is to show how the microstructure of ingots is being formed during semi-continuous casting. The chemical profiles of ingots were determined using optical emission spectroscopy. Chemical analysis in micro-areas with evaluation by scanning electron microscope SEM with EDS analyzer was performed and the distribution of chemical elements in the microstructures are also presented. An XRD detector was used to show specific phases in the alloys. The grains are formed in a particular way during crystallization. In the middle of the ingot – further away from the crystallizer – the grains are larger. Semi-continuous casting together with homogenization enables the production of ingots with uniform cross sections as can be seen in the paper.

PL

Badania prowadzono dla dwóch wybranych stopów aluminium serii 7xxx zgodnie z PN-EN 573-3:2010 – wersja polska. Ocenę wlewków prowadzono na stopach 7003, 7003S oraz 7010, 7010K o zbliżonej zawartości cyrkonu. Oznaczenia S i K to modyfikacja wewnętrzna, nadal zgodna z normą. Wlewki wykonane zostały na drodze odlewania półciągłego. Stopy aluminium tej serii, o podwyższonych właściwościach, przeznaczone są do przeróbki plastycznej. Celem publikacji jest pokazanie, w jaki sposób kształtuje się mikrostruktura wlewków podczas półciągłego odlewania. Profile chemiczne wlewków wykonano przy wykorzystaniu optycznej spektroskopii emisyjnej. Wykonano również badania mikrostruktury wraz z analizą składu chemicznego w mikroobszarach z wykorzystaniem mikroskopu skaningowego (SEM) z analizatorem EDS oraz zaprezentowano rozkład pierwiastków na mikrostrukturach. Do wskazania konkretnych faz w stopach zastosowano detektor XRD. Ziarna podczas krystalizacji wlewków kształtują się w charakterystyczny sposób. Średnica ziaren zwiększa się w kierunku środka wlewka, wraz z oddalaniem się od krystalizatora. Półciągłe odlewanie w połączeniu z homogenizacją umożliwia wykonanie wlewków o jednolitym przekroju poprzecznym, co zostało zaprezentowane w pracy.

8

Correlation between mechanical properties of selected 7xxx series aluminum alloys obtained by semi-continuous casting

Kwak Z., Garbacz-Klempka A., Perek-Nowak M., Szymański Ł.

Metallurgy and Foundry Engineering

|

2016

|

Vol. 42, no. 1

69--78

EN

The studied ingots were made of alloys with a similar zirconium ratio, typically be given as: EN AW-7010 [AlZn6MgCu] and EN AW-7003 [Al Zn6Mg0,8Zr], in accordance with European standard PN-EN 573-3:2014-02 English version. The symbols S and K are our internal modifications, compatible with the standard. The added zirconium was intended to improve the tensile strength resulting from plastic forming and an increasing resistance to cracking. Samples were taken from ingots made in the process of semi-continuous casting, some of which were homogenized; however, non-homogenized samples were also analyzed. The tests of tensile strength for the 7003, 7003S, and 7010K alloys were conducted longitudinally and transversely to the casting direction.The tensile strength test for 7010 was conducted only transversely to the direction of casting. The aim of this publication is to present the results of strength test sand to show a correlation between the basic properties of 7xxx-series aluminum alloys; i.e., relative elongation E, yield strength YS, and ultimate tensile strength UTS.

PL

Ocenę wlewków prowadzono na stopach o zbliżonej zawartości cyrkonu, zazwyczaj podawanych jako EN AW-7010 [AlZn6MgCu] and EN AW-7003 [AlZn6Mg0,8Zr], zgodnie z europejską normą PN-EN 573-3:2014-02 – wersja angielska. Obecne w pracy oznaczenia K, S to modyfikacja wewnętrzna zgodna z normą. Wprowadzony cyrkon ma za zadanie poprawę właściwości wytrzymałościowych stopów otrzymanych na drodze przeróbki plastycznej oraz zwiększenie ich odporności na pękanie. Próbki zostały pobrane z wlewków otrzymanych na drodze odlewania półciągłego, w stanie niehomogenizowanym i homogenizowanym. Badania wytrzymałości na rozciąganie przeprowadzano w kierunku podłużnym i poprzecznym w odniesieniu do kierunku odlewania stopów 7003, 7003S i 7010K. Dla stopu 7010 wytrzymałość na rozciąganie badano w próbie poprzecznej do kierunku odlewania. Celem publikacji jest prezentacja wyników badań właściwości wytrzymałościowych. Praca ma również na celu pokazanie korelacji pomiędzy podstawowymi właściwościami, tj. wydłużeniem względnym A, umowną granicą plastyczności Rp0,2 a wytrzymałością na rozciąganie Rm.

9

Joining of Low-Carbon Steel Sheets with Al-Based Weld

Boczkal G., Perek-Nowak M., Majewska Z.

Archives of Metallurgy and Materials

|

2016

|

Vol. 61, iss. 1

37--42

EN

The analysis of the connection steel/Al/steel made by resistance welding was performed. The used low-carbon steel had low content of carbon and other elements, aluminum was of 99.997 wt.% Al purity. Formation of various FeAl intermetallic phases found in the phase diagram depending on the duration of the process was analyzed. Two distinctively different types of structure depending on time of welding were observed: 1) hypoeutectic structure for samples processed for 5 s, and 2) eutectic structure for samples processed for 10 s and more. The shear test showed increase of mechanical properties of the connection for the samples welded 10 s.

10

Formation of Transition Phases on Interface between Monocrystalline Fe and Cu Due to Mutual Solid-State Diffusion

Perek-Nowak M., Boczkal G.

Archives of Metallurgy and Materials

|

2016

|

Vol. 61, iss. 2A

581--586

EN

Interdiffusion between Fe (Armco) and Cu single crystals of similar orientation (around [110]) annealed at temperatures of 873 and 973K in air for 0.5 up to 4 h is studied. Formation of three phases different in their chemical composition has been observed: 1) oxide layer on Cu border (porous), 2) a layer rich in copper, iron and oxygen, 3) a layer of iron and oxygen with only small addition of Cu. All reactions of interface formation occurred in solid state. It was noted that oxygen plays an important role in development of new phases. Strong Kirkendall effect is observed due to large difference in diffusion coefficients of copper atoms to iron, DCu→Fe=300exp(-67800/RT) and iron atoms to copper DCu→Fe=0.091exp(-46140/RT).

11

Archaeometallurgical Investigations of the Early Iron Age Casting Workshop at Kamieniec. A Preliminary Study

Garbacz-Klempka A., Kowalski Ł., Kozana J., Gackowski J., Perek-Nowak M., Szczepańska G., Piękoś M.

Archives of Foundry Engineering

|

2016

|

Vol. 16, iss. 3

29--34

EN

(Chełmno land, Poland) as it is reflected through casting workshop recovered during recent excavations. Among ready products, the ones giving evidence of local metallurgy (e.g. casting moulds and main runners) were also identified. With the shrinkage cavities and dendritic microstructures revealed, the artifacts prove the implementing a casting method by the Lusatian culture metalworkers. The elemental composition indicates application of two main types of bronzes: Cu-Sn and Cu-Pb. Aside these main alloying additions, some natural impurities such as silver, arsenic, antimony and nickel were found which may be attributed to the origin of the ore and casting technology. The collection from Kamieniec was described in terms of its structure and composition. The investigations were made by means of the energy dispersive X-ray fluorescence spectroscopy (ED-XRF), scanning electron microscopy (SEM) coupled with an energy dispersive X-ray analysis system (EDS) and optical microscopy (OM). In order to fingerprint either local or non-local profile of the alloys, the ED-XRF data-set was statistically evaluated using a factor analysis (FA).

12

Effect Of Severe Plastic Deformation On Microstructure Evolution Of Pure Aluminium

Leszczyńska-Madej B., Richert M. W., Perek-Nowak M.

Archives of Metallurgy and Materials

|

2015

|

Vol. 60, iss. 2B

1437--1440

EN

Processes of severe plastic deformation (SPD) are defined as a group of metalworking techniques in which a very large plastic strain is imposed on a bulk material in order to make an ultra-fine grained metal. The present study attempts to apply Equal-Channel Angular Pressing (ECAP), Hydrostatic Extrusion (HE) and combination of ECAP and HE to 99.5% pure aluminium. ECAP process was realized at room temperature for 16 passes through route Bc using a die having an angle of 90°. Hydrostatic extrusion process was performed with cumulative strain of 2.68 to attain finally wire diameter of d = 3 mm. The microstructure of the samples was investigated by means of transmission and scanning electron microscopy. Additionally, the microhardness was measured and statistical analysis of the grains and subgrains was performed. Based on Kikuchi diffraction patterns misorientation was determined. The measured grain/subgrain size show, that regardless the mode of deformation process (ECAP, HE or combination of ECAP and HE processes), grain size is maintained at a similar level – equal to d = 0.55-0.59 μm. A combination of ECAP and HE has achieved better properties than either single process and show to be a promising procedure for manufacturing bulk UFG aluminium.

13

The Properties of 7xxx Series Alloys Formed by Alloying Additions

Kwak Z., Rzadkosz S., Garbacz-Klempka A., Perek-Nowak M., Krok W.

Archives of Foundry Engineering

|

2015

|

Vol. 15, iss. 2

59--64

EN

Currently there is a constant development in the field of aluminium alloys engineering. This results from, i.a., better understanding of the mechanisms that direct strengthening of these alloys and the role of microalloying. Now it is microalloying in aluminum alloys that is receiving a lot of attention. It affects substantially the macro- and microstructure and kinetics of phase transformation influencing the properties during production and its exploitation. 7xxx series aluminum alloys, based on the Al-Zn-Mg-Cu system, are high-strength alloys, moreover, the presence of Zr and Sr further increases their strength and improves resistance to cracking. This study aims to present the changes of the properties, depending on the alloy chemical composition and the macro- and microstructure. Therefore, the characteristics in the field of hardness, tensile strength, yield strength and elongation are shown on selected examples. Observations were made on ingot samples obtained by semi-continuous casting, in the homogenized state. Samples were prepared from aluminum alloys in accordance with PN-EN 573-3: 2013. The advantage of Al-Zn-Mg-Cu alloys are undoubtedly good strength, Light-weight and resistance to corrosion. As widening of the already published studies it is sought to demonstrate the repeatability of the physical parameters in the whole volume of the sample.

14

The Metallographic Characterization of Metal Artifacts Based on Late Medieval Examples

Garbacz-Klempka A., Kwak Z., Perek-Nowak M., Starski M.

Archives of Foundry Engineering

|

2015

|

Vol. 15, iss. 4 spec.

29--34

EN

This work presents the metallographical observations of the chosen copper objects from the Late Middle Ages. Part of these studies is the analysis of metal relics from the Puck area conducted at the Faculty of Foundry, AGH-UST, in collaboration with the University of Warsaw. Medieval European cities were centers of trade and production of metal artifacts. Also in the Puck area, the manufacturing activities can be confirmed based on the metal findings. The aim of this study was to identify and systematize copper alloys used in the Late Medieval Period, on the basis of historic artifacts from Puck. The chemical composition analysis and microstructure observation were carried out. The research is at the first stage of an experiment of reconstructing the medieval alloys in order to study deeper their properties.

15

Research of Aluminium Influence on Tin Bronzes

Rzadkosz S., Garbacz-Klempka A., Kozana J., Piękoś M., Czekaj E., Perek-Nowak M.

Archives of Foundry Engineering

|

2015

|

Vol. 15, iss. 1 spec.

93--98

EN

During the research a group of copper and tin alloys was investigated. The influence of variable additions of aluminium within the range of 0.3 – 1.4 wt % was analysed on tin bronze CuSn10 with the aim of obtaining durable bronzes, from outside the normalized copper alloy groups. Melts were conducted in order to obtain alloy samples for testing the chosen properties. Metallographic and SEM-EDS tests were carried out to determine the microstructure changes caused by introducing Al addition to CuSn10 alloy. Also, chosen mechanical properties were tested for the alloys investigated. The results showed considerable changes in the microstructure as well as significant hardening of the Cu-Sn alloys as the result of aluminium addition. The thermal and dilatometric analysis confirmed the presence of phase changes, also their parameters were assessed depending on the share of aluminium addition in the CuSn10. The aluminium additive applied within the range of 0.3-1.4 wt% to CuSn10 bronze clearly impacted the microstructure and the strength properties analysed, causing the increase in strength and hardness with simultaneous insignificant decrease of elongation of the CuSn10Al alloys.

16

Copper and Arsenical Copper During Eneolithic in Metallographic and Mechanical Properties Examination

Garbacz-Klempka A., Kozana J., Piękoś M., Cieślak W., Perek-Nowak M., Kowalski Ł., Adamczak K., Łoś J.

Archives of Foundry Engineering

|

2015

|

Vol. 15, iss. 4 spec.

23--28

EN

Arsenical copper has been used since 5th millennium cal.BC, later exchanged by application of Cu-Sn alloys in metallurgy. This work presents the results of metallographic and mechanical properties studies performed on two flat axes connected with local Eneolithic societies (4500-3000 cal.BC). The axes are one of the oldest metal artifacts from Polish land. Originally they were made from Cu-As alloy, and their chemical composition was established by X-ray fluorescence spectroscopy (XRF). Their microstructure was analysed using optical microscopy (OM) and scanning electron microscopy conducted with energy-dispersive X-ray spectroscopy (SEM-EDS). The macrostructure analysis (OM) of the axes was performed as well. On the basis of the results, the alloys used in the Eneolithic to cast the axes were reproduced in lab. In order to achieve the characteristics of the alloys, their mechanical properties including ultimate tensile strenght (UTS), hardness (HB), microhardness (HV0,1) and ductility were examined. The solidification process was studied by means of thermal analysis.

17

Reconfiguration of Point Defects in FCC and HCP Metals at Initial Stage of Recovery Process

Boczkal G., Perek-Nowak M.

Archives of Metallurgy and Materials

|

2014

|

Vol. 59, iss. 4

1321--1325

EN

The conducted studies regarded the analysis of change of structure of point defects occurring during initial stage of recovery of FCC (Al, Cu) and HCP (Ti, Mg and Zn) metals at temperature close to Th =0.5Tm. The changes in resistivity of the deformed and later recovered samples were measured. The recovery time was 1, 2, 3, 4 or 5 min. The observed changes were correlated with reorganization of arrangement of lattice defects during annealing.

PL

Przeprowadzone badania dotyczyły analizy zmian struktury defektów sieciowych, zachodzących w początkowym okresie zdrowienia metali RSC (Al, Cu) oraz HZ (Ti, Mg oraz Zn) w temperaturze zblizonej do T=0.5 Tm. Badano zmiany oporu właściwego odkształconych próbek poddanych zdrowieniu przy czasach 1, 2, 3, 4 lub 5 min. Obserwowane zmiany skorelowano z reorganizacja struktury defektów sieciowych podczas wyżarzania. Uzyskane wyniki pokazały, że w przypadku metali o sieci RSC spadek oporności właściwej w funkcji czasu zdrowienia maleje monotonicznie, co świadczy o postępującej anihilacji defektów strukturalnych. Dla sieci HZ stwierdzono, że zmiany te mają charakter oscylacyjny z minimum występującym po czasie około 1-2 min. Świadczy to o rekonfiguracji defektów sieciowych i tworzeniu się w początkowym stadium zdrowienia złożonych, niestabilnych termodynamicznie struktur (układy wakancji, petle, zarodki dyslokacji), które powodują chwilowy efekt oczyszczenia struktury i w konsekwencji spadek oporu właściwego poniżej poziomu właściwego dla struktury całkowicie poddanej zdrowieniu, charakteryzującej się równowagową koncentracją wakancji.

18

Structure and electrical properties of Sn8Zn solder alloy with Ag and Ga additions

Boczkal G., Perek-Nowak M.

Metallurgy and Foundry Engineering

|

2013

|

Vol. 39, no. 1

39--45

EN

Solder joints based on eutectic SnZn alloy were studied. The influence of Ga and Ag was analysed and compared to the basic Sn8Zn alloy as well as to the reference solder alloys Sn60Pb40 and Sn3Cu. The formation of intermetallic layer in zinc-containing alloys made mainly out of Cu5Zn8 type was noted, while in the standard solder alloys it was Cu3Sn. The resistivity measurements showed the lowest value for Sn8Zn1 Ag and the worst in the case of Sn8Zn1 Ga, due to the quite different incorporation of Ag and Ga atoms in the solder: Ag atoms are found in precipitates while Ga atoms are dissolved in the matrix.

PL

W pracy przedstawiono badania dotyczące połączeń lutowanych na bazie stopu eutektycznego SnZn. Porównano wpływ dodatków stopowych Ga i Ag w stosunku do referencyjnego stopu Sn8Zn i stopów lutowniczych Sn60Pb40 i Sn3Cu. Zauważono wytworzenie warstwy międzymetalicznej w stopach zawierających cynk, która zbudowana była głównie ze związku typu Cu5Zn8, podczas gdy w standardowych stopach jest to zwykle faza Cu3Sn. Badania oporności wykazały najniższą wartość dla stopu Sn8ZnAg, a najwyższą dla stopu Sn8ZnGa, ze względu na różny sposób rozmieszczenia atomów Ag i Ga w połączeniu lutowanym: atomy Ag znajdują się w wydzieleniach, a Ga są rozpuszczone w osnowie.

19

The influence of soldering conditions on conductivity, structure and strength of Cu/Sn96Ag4 solders

Boczkal G., Marecki P., Perek-Nowak M.

Archives of Metallurgy and Materials

|

2012

|

Vol. 57, iss. 1

33-37

EN

In the paper the electrical properties of the Cu/Sn96Ag4 solders were studied. The studied solders were produced at 200, 220 and 250°C and within time range 3 to 90 s. Soldering temperatures were chosen to assure the best soldering conditions for the Cu/Sn96Ag4 alloy. The most appropriate temperature of 200°C is the one just above the melting point. The temperature of 250°C is the maximal one recommended by producers, which can be applied for the electronic elements during soldering. The studies have shown that the best electrical properties and tensile strength Rm have samples soldered at times 3 and 30 s, while the highest specific resistance together with the lowest Rm value are observed for samples soldered at the time of 10 s. The soldering temperature have small influence on the strength of the connection/bond however it shows significant affect on the electrical properties.

PL

W pracy badano własności elektryczne i mechaniczne połączeń lutowanych Cu/Sn96Ag4. Badane połączenia wykonywano przy temperaturach 200, 220 i 250°C oraz przy czasach lutowania z zakresu od 3 do 90 s. Temperatury lutowania zostały dobrane pod kątem warunków w jakich może być prowadzony proces lutowania przy użyciu stopu Cu/Sn96Ag4. Odpowiednia temperatura 200°C jest tuż powyżej punktu topnienia, a więc najniższa możliwa do zastosowania. Temperatura 250°C jest maksymalną zalecaną przez producentów temperaturą, którą mogą wytrzymać elementy elektroniczne podczas lutowania. Badania wykazały, że najlepsze własności elektryczne oraz wytrzymałość na rozciąganie Rm wykazują próbki lutowane przy czasach 3 i 30 s, natomiast najwyższy opór właściwy połączony z najniższą wartością Rm zaobserwowano dla próbek lutowanych w czasie 10s. Temperatura lutowania ma niewielki wpływ na wytrzymałość połączenia natomiast w istotny sposób wpływa na własności elektryczne.

20

Microstructure of AgSnBi powder consolidated in reciprocating extrusion process

Richert M. W., Richert J., Hotloś A., Perek-Nowak M., Tokarski T., Skiba J.

Archives of Materials Science and Engineering

|

2012

|

Vol. 58, nr 2

120--124

EN

Purpose: The AgSnBi powder used for electrical contacts has been consolidated in the process of reciprocating extrusion (cyclic extrusion compression - CEC) in 2, 4, 8 and 16 CEC cycles at room temperature. It corresponds to the deformations: 2 CEC cycles - ϕ = 0.84, 4 CEC cycles - ϕ = 1.68, 8 CEC cycles - ϕ = 3.36 and 16 CEC cycles - ϕ = 6.72. The microstructure of consolidated powder has been characterized by optical microscopy (MO), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found characteristic granular microstructure with the oxides film at granular boundaries. Some voids and cracks were observed in consolidated samples, especially at higher magnifications. Inside the consolidated granules the nano-microstructure with nano - twins was found. Microhardness of AgSnBi after the consolidation by the CEC process achieved level of about 100-110 μHV. The microhardness of samples consolidated by CEC and then hydrostatically extruded increase of about 20 μHV units. Design/methodology/approach: The investigations of microstructure were performed by optical microscopy (MO) Olympus GX51, and scanning electron microscopy SU-70 with field emission gun thermally aided. The microhardness of consolidated samples was measured by Vickers method. Findings: The microstructures of consolidated AgSnBi powders were observed and analyzed. On the base of the microstructure and microhardness investigations the mechanisms of formation of bulk material from powder by severe plastic deformation (SPD) methods was discussed. Practical implications: The performed investigations contribute to the understanding of processes of deformation in the range of unconventional strains exerted by the SPD methods. The new way of consolidation of powders using to the production of electrical contacts was presented. Originality/value: It was assumed that AgSnBi powder consolidated by CEC and hydrostatic extrusion exhibited the nano-microstructure.