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1

Magnetostrictive Functional Materials of Tb0.27Dy0.73(Fe1-xAlx)2 Series as Prospective Constituents of Magnetoelectric Composites

Winiarska Barbara, Guzdek Piotr, Kuciakowski Juliusz, Tokarz Waldemar, Sikora Marcin, Pszczoła Jarosław

Archives of Metallurgy and Materials

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2023

|

Vol. 68, iss. 1

215--222

EN

Structural, magnetic, and magnetostrictive properties of two-sublattice Tb0.27Dy0.73(Fe1-xAlx)2 polycrystalline intermetallic ferrimagnets (x = 0-0.2 and 1.0) were studied using X-ray powder diffraction, magnetometry, and strain gauge magnetostriction measurements. Temperature dependences of magnetization starting from 80 K were presented, and Curie temperatures were estimated. Coercive force, residual, and saturation magnetizations were determined from the magnetic hysteresis loops at room temperature. Longitudinal, transversal, form and volume magnetostrictions were investigated against the x parameter and the intensity of the magnetic field. The piezomagnetic coefficients were determined and the maximum value at the field below 1 kOe, even enhanced than that in Terfenol-D, was observed for the material TTb0.27Dy0.73(Fe0.9Al0.1)2. It means that this compound is promising for use in magnetoelectric composites.

2

Precipitation of Sigma and Chi Phases in Cast Standard Duplex Stainless Steel

Myška Martin, Bořil Petr, Krutiš Vladimír, Kaňa Václav, Zádĕra Antonin

Archives of Foundry Engineering

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2023

|

Vol. 23, iss. 2

29--34

EN

This work deals with the problem of intermetallic phases in cast standard duplex steel ASTM A890 Gr 4A (generally known as 2205). The investigated steel was subjected to isothermal heat treatment in the range from 595 °C to 900 °C and in the duration from 15 minutes to 245 hours, and was also investigated in terms of anisothermal (natural) cooling after casting into the mould. The precipitation starts at grain boundaries with a consistent ferrite transformation. The work is focused on the precipitation of the sigma phase (σ) and the chi phase (χ). Examination of the microstructure was conducted using light and scanning electron microscopy. Their statistical analysis was carried out using the results of the investigations of precipitation processes in the microstructure, both within the grains and at the grain boundaries. To illustrate this impact, the surface area of precipitates was evaluated. The percentage of these intermetallic phases was calculated by measuring their area using a computer image analysis system. Based on their observations, a combined time-temperature transformation (TTT) diagram with continuous cooling transformation (CCT) curves was created.

3

The formation of Si-aluminide coating formed by plasma spraying and subsequent diffusion annealing on Ti-Al-7Nb intermetallic alloy

Góral M., Monteiro P.C., Sosnowy C., Woźniak M., Kubaszek T., Kościelniak B.

Archives of Materials Science and Engineering

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2022

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Vol. 117, nr 2

49--56

EN

Purpose: In the article, the kinetic growth phenomena of aluminide coating formed by plasma spraying pure Al-Si powder and subsequent diffusion annealing on TiAl intermetallic alloy in inert atmosphere were investigated. Design/methodology/approach: The Al-Si powder was thermal sprayed (APS) on TiAl7Nb intermetallic alloy and annealed in Ar atmosphere during 5, 15, 30, 60, 240 and 480 min. The kinetic growth of the coating was observed using the scanning electron microscopy method (SEM), and chemical composition was analysed using the EDS method. Findings: The Kirkendall Effects pores formation, as well as titanium silicides on the grain boundary of TiAl3, was found. Research limitations/implications: The oxidation resistance of the developed coating might be analysed in further work. Practical implications: The developed coating might be used for the production of protective aluminide coatings on TiAl intermetallic alloys. Originality/value: The description of aluminide coating formation in a new technological process.

4

Measurements of huge magnetostriction of the heavy rare earth – iron intermetallics

Pszczoła Jarosław, Cetnar Tomasz

Physics for Economy

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2021

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Vol. 4

65-74

EN

The method described in this work is the strain gauge method used to measure huge magnetostriction of the heavy rare earth - iron intermetallics. The measuring system and the procedure of measurement are presented in this work. The results of huge magnetostriction determined for the heavy rare earth-iron compounds with the MgCu2 - type crystal structure are shown.

5

Comparison of corrosion kinetics of metallic- and ionic materials for negative composite electrodes of NiMH type battery

Zayani Wissem, Dymek Martyna, Bala Henryk

Ochrona przed Korozją

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2021

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nr 4

100-105

EN

Capacity fade and exchange current density of H2O/H2 system have been compared in conditions of long-standing cycling for powder composite electrodes based on (i) Sm0.4Zn0.6Fe2O4 ferrite spinel and (ii) LaNi4.5Co0.5 intermetallic compound. Changes of both quantities have been presented versus electrodes exposure time in strong alkaline solutions, at room temperature. Corrosion rate of semiconducting ferrite spinel is about 2.5 times lower than that of the intermetallic material. Consequently, capacity half-time is distinctly longer for the ferrite electrode. On the other hand, exchange current density of H2O/H2 system for ferrite spinel is extraordinarily low, on the level of 7 – 8 mA/g. It is suggested surface modification of the ferrite spinel material to improve its catalytic properties towards H2O/H2 redox system.

PL

Porównano spadki pojemności właściwej i gęstości prądu wymiany układu H2O/H2 spowodowane długotrwałym cyklowaniem dwu typów proszkowych elektrod kompozytowych: (a) spinelu ferrytowego Sm0.4Zn0.6Fe2O4 i (b) związku międzymetalicznego LaNi4.5Co0.5. Zmiany obydwu wielkości przedstawiono w funkcji czasu ekspozycji elektrod w silnie alkalicznych roztworach, przy temperaturze pokojowej. Szybkość korozji materiału półprzewodnikowego, jakim jest spinel ferrytowy okazała się ok. 2,5 razy mniejsza niż związku międzymetalicznego. W konsekwencji, czas połówkowego obniżenia pojemności jest wyraźnie dłuższy dla elektrody ferrytowej. Z drugiej jednak strony, gęstość prądu wymiany układu H2O/H2 dla elektrody ferrytowej jest wyjątkowo mała, na poziomie 7 – 8 mA/g. Zasugerowano modyfikację elektrody ferrytowej dla poprawy jej właściwości katalitycznych w odniesieniu do układu redoks H2O/H2.

6

Enhanced magnetoelastic performance in Pr/Mn-doped Laves phase (Tb,Ho)Fe2 compounds

Wang M. K., Liu J. J., Lv X. J., Ding Q. L., Li F., Pan Z. B., Xia W. X., Du J.

Materials Science Poland

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2020

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Vol. 38, No. 4

707--714

EN

Magnetostrictive TbxHo0.8−xPr0.2Fe1.8Mn0.1 (0 ⩽ x ⩽ 0.20) alloys are prepared by arc-melting and subsequent annealing. The dopant of Pr/Mn introduced into RFe2 compounds effectively stabilizes the forming of single C15 Laves phase at ambient pressure. The easy magnetization direction (EMD) varies when Tb content increases, which is accompanied by a crystalstructural transition. EMD lies along ‹1 0 0› axis for x ⩽ 0.05, rotating to ‹1 1 1› axis for x ⩽ 0.12, with a tetragonal symmetry changing to a rhombohedral one. Magnetocrystalline-anisotropy compensation is obtained with the optimized composition of x = 0.12, shifting to the Tb-poor side in comparison to Pr/Mn-free counterpart. An enhanced effect on magnetoelastic properties is achieved in Tb0.12Ho0.68Pr0.2Fe1.8Mn0.1, which simultaneously possesses a low anisotropy and high magnetostriction performance, i.e. λs ~ 420 ppm, λ111 ~ 970 ppm, and a large low-field λa ~ 390 ppm/2 kOe, being 30 % higher than that of Pr/Mn-free compound. Combining low-cost light rare earth Pr with the lower Tb content, Tb0.12Ho0.68Pr0.2Fe1.8Mn0.1may make it promising solution in magnetostrictive applications.

7

Effect of deformation temperature and strain rate on compressive behavior of laminated aluminum bronze-intermetallic composites

Konieczny Marek

Composites Theory and Practice

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2020

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R. 20, nr 1

43--48

EN

Laminated composites were produced by reactive bonding using CuAl10Fe3Mn2 bronze and titanium foils with thicknesses of 0.6 and 0.1 mm, respectively. To obtain the composite sample five foils of bronze and four of titanium were used. During fabrication, the titanium layers reacted completely and formed intermetallics (Ti2Cu, TiCuAl and TiCu2Al). In order to investigate the compressive behavior of the laminated CuAl10Fe3Mn2-intermetallic composites, isothermal compression tests were conducted at the temperatures of 20, 600 and 800°C with two different strain rates of 1·10-3 s-1 and 2.9·10-3 s-1. The thickness of all the specimens was reduced by 50%. During the compression tests delamination of the layers of the composites was not observed. With an increase in the investigation temperature the yield strength of the composites decreased significantly. The results showed that the deformation temperature and the strain rate were equally responsible for the evolution of deformation during isothermal compression. The most favorable compressive deformation conditions necessary to shape the laminated CuAl10Fe3Mn2-intermetallic phases composites without damaging their layers were determined experimentally.

PL

Wytworzono kompozyty warstwowe z foli z brązu aluminiowego CuAl10Fe3Mn2 o grubości 0,6 mm oraz z foli tytanowej o grubości 0,1 mm. W celu uzyskania kompozytu zastosowano pięć folii z brązu i cztery z tytanu. Podczas reakcji syntezy warstwy tytanu całkowicie przereagowały i powstały fazy międzymetaliczne (Ti2Cu, TiCuAl i TiCu2Al). W celu przeanalizowania mechanizmu deformacji podczas ściskania kompozytów przeprowadzono testy w temperaturze 20, 600 i 800°C, stosując dwie różne prędkości odkształcania: 1·10-3 s-1 oraz 2,9·10-3 s-1. Próby prowadzono do uzyskania 50% redukcji grubości. Podczas prób ściskania nie zaobserwowano delaminacji warstw kompozytu. Stwierdzono znaczny spadek granicy plastyczności kompozytów wraz ze wzrostem temperatury badania. Wyniki pokazały, że zarówno temperatura, jak i prędkość odkształcania miały wpływ na mechanizm deformacji. Eksperymentalnie określono optymalne parametry procesu odkształcania kompozytu CuAl10Fe3Mn2-fazy międzymetaliczne pozwalające na jego kształtowanie bez niszczenia warstw.

8

Characterization of dissimilar Al-Cu BFSW welds; interfacial microstructure, flow mechanism and intermetallics formation

Tamadon A., Abdali M., Pons D. J., Clucas D.

Advances in Materials Science

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2020

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Vol. 20, nr 3(65)

52--78

EN

The purpose of this study is to elucidate the flow features of the dissimilar Al-Cu welded plates. The welding method used is Bobbin Friction Stir Welding (BFSW), and the joint is between two dissimilar materials, aluminium alloy (AA6082-T6) and pure copper. Weld samples were cut from along the weld line, and the cross-sections were polished and observed under an optical microscope (OM). Particular regions of interest were examined under a scanning electron microscope (SEM) and analysed with Energy Dispersive X-ray Spectroscopy (EDS) using the AZtec software from Oxford Instruments. The results and images attained were compared to other similar studies. The reason for fracture was mainly attributed to the welding parameters used; a higher rotational speed may be required to achieve a successful BFSW between these two materials. The impact of welding parameters on the Al-Cu flow bonding and evolution of the intermetallic compounds were identified by studying the interfacial microstructure at the location of the tool action. The work makes an original contribution to identifying the solid-phase hybrid bonding in Al-Cu joints to improve the understanding of the flow behaviours during the BFSW welding process. The microstructural evolution of the dissimilar weld has made it possible to develop a physical model proposed for the flow failure mechanism.

9

Characterization of Bonded Zone and Evaluation of Cracking in Vacuum Brazed Zircaloy-4 and Stainless Steel-316L Joint

Munis A., Zheng Maosheng, Akhter J. I., Ahmad M.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 2

707--713

EN

Brazing of two dissimilar structural materials; Zircaloy-4 and SS-316L was performed at 900°C under high vacuum conditions. The metallic glass ribbons (Zr55Cu30Al10Ni2Fe3-at.%) of 30 μm thickness, were used as an interlayer. The bonded region was characterized by scanning electron microscope (SEM), energy dispersive spectroscope (EDS) and microhardness testing. The metallurgical bond formation was due to compositional changes in the molten interlayer and later on its subsequent solidification. Assessment of the bonded zone (BZ) revealed three distinct regions (Region-I, Region-II and Region-III). Diffusion transformation was observed in Region-I and Region-III which were interface with base alloys SS-316L and Zircaloy-4 respectively. However, Region-II at the middle of the BZ was composed of isothermally and athermally solidified portions. The highest values of Microhardness were observed in Region-III which was due to the presence of hard phases. Moreover, a crack parallel to BZ was observed in Region-III and was attributed to differential contraction of base alloys during cooling. Maximum shear stress acting on the BZ was calculated and correlated to the brittle phase cracking.

10

Microstructure and Mechanical Properties of Friction Stir Welded Joints between Commercially Pure Copper and Al 6351 Alloy

Sinha V. C., Kundu S., Chatterjee S.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 3

1819--1825

EN

In the present study, the effect of tool rotational speed on microstructure and mechanical properties of friction stir welded joints between commercially pure copper and 6351 Al alloy was carried out in the range of tool rotational speeds of 300-900 rpm in steps of 150 rpm at 30 mm/minutes travel speed. Up to 450 rpm, the interface of the joints is free from intermetallics and Al4 Cu9 intermetallic has been observed at the stir zone. However, Al4 Cu9 intermetallic was observed both at the interface and the stir zone at 600 rpm. At 750 and 900 rpm tool rotational speed, the layers of AlCu, Al2 Cu3 and Al4 Cu9 intermetallics were observed at the interface and only Al4 Cu9 intermetallics has been observed in the stir zone. The maximum ultimate tensile strength of ~207 MPa and yield strength of ~168 MPa along with ~6.2% elongation at fracture of the joint have been obtained when processed at 450 rpm tool rotational speed.

11

Kucie w plastycznej matrycy intermetalików TiAl

Szczepanik S., Bednarczyk P.

Rudy i Metale Nieżelazne Recykling

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2016

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R. 61, nr 3

121--125

PL

Przedstawiono wyniki badań materiałów Ti-Al otrzymanych z mieszanki proszków przez prasowanie, a także w procesie samorozwijającej się syntezy SHS i dodatkowym odkształceniu w plastycznej matrycy. Po odkształceniu w plastycznej matrycy nastąpiło zwiększenie gęstości wyrobów oraz poprawa ich twardości i wytrzymałości na zginanie. Otrzymane materiały o porowatości 2,54 i 3,89% mają strukturę złożoną z ziaren fazy γ czyli TiAl, oraz płytkowych ziaren fazy γ i α2-Ti3Al.

EN

The influence of hot forging in a fluid die of hot pressed and of SHS Ti-Al powder preforms on structure and properties was investigated. Processing increased the density, with the materials having 2.54 and 3.89% porosity, respectively. The structures comprised γ-TiAl grains and γ and α2-Ti3Al platelets. Hardness was 183 ±34 HV10 for the previously hot pressed materials and 147 ±3 HV10 for SHS performs, and bends strengths were 146 MPa and 247 MPa, respectively.

12

Modelowanie wstępnego prasowania proszków metodą elementów dyskretnych

Jurczak K., Rojek J., Nosewicz S., Lumelskyy D., Bochenek K., Chmielewski M., Pietrzak K.

Hutnik, Wiadomości Hutnicze

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2016

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Vol. 83, nr 1

3--7

PL

W niniejszym artykule zaprezentowano wyniki modelowania zagęszczania proszku stanowiącego wstępny etap procesu prasowania na gorąco. Modelowanie numeryczne zrealizowano metodą elementów dyskretnych z wykorzystaniem kulistych cząstek. Analizę skoncentrowano na badaniu mechanizmów zagęszczania proszku przy ciśnieniu do 50 MPa oraz poszukiwaniu modeli odpowiednich przy zastosowanych warunkach realizacji procesu. Symulacje numeryczne wykonano wykorzystując dwa modele oddziaływania cząstek proszku: sprężysty model Hertza-Mindlina-Deresiewicza oraz plastyczny model Storåkersa. Wyniki numeryczne zostały porównane z wynikami laboratoryjnymi prasowania proszku NiAl. Otrzymano dużą zgodność wyników eksperymentalnych i numerycznych.

EN

This paper presents the results of discrete element simulation of powder compaction which is the initial stage in the hot pressing process. Numerical simulation has been performed by discrete element method with using spherical particles. The research has been focused on densification mechanisms under pressure 50 MPa and models appropriate for these conditions. Numerical simulations have been carried out for two contact models: elastic Hertz-Mindlin-Deresiewicz and plastic – Storåkers. Numerical results and results from laboratory test of the uniaxial pressing of NiAl powder have been compared. The obtained results of numerical simulation and laboratory tests showing a good agreement.

13

Joining of the AMC Composites Reinforced with Ti3Al Intermetallic Particles by Resistance Butt Welding

Adamiak M., Tomiczek B., Górka J., Czupryński A.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 2A

847--852

EN

The introduction of new reinforcing materials continues to be investigated to improve the final behaviour of AMCs as well as to avoid some drawbacks of using ceramics as reinforcement. The present work investigates the structure, properties and ability of joining aluminium EN-AW 6061 matrix composite materials reinforced with Ti3Al particles by resistance butt welding as well as composite materials produced by mechanical milling, powder metallurgy and hot extrusion techniques. Mechanically milled and extruded composites show finer and better distribution of reinforcement particles, which leads to better mechanical properties of the obtained products. Finer microstructure improves mechanical properties of obtained composites. The hardness increases twice in the case of mechanically milled composites also, a higher reinforcement content results in higher particle dispersion hardening, for 15 wt.% of intermetallics reinforcement concentration composites reach about 400 MPa UTS. Investigation results of joints show that best hardness and tensile properties of joints can be achieved by altering soft conditions of butt welding process e.g. current flow time 1.2 s and current 1400 A. To improve mechanical properties of butt welding joints age hardening techniques can also be used.

14

The influence of the surface roughness on the oxidation behavior of Ti-25Al-12Nb alloy : surface layer characteristic

Małecka J.

Ochrona przed Korozją

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2015

|

nr 3

75--81

EN

The paper presents test results of the oxidation of Ti-25Al-12Nb alloy taking into account the effect of surface roughness. Oxidation was carried out in air at the temperature of 800ºC. It was determined that the rise in surface roughness improves oxidation resistance. This paper characterizes the geometrical structure of the surface and the adhesion of the growing oxide layers.

PL

W pracy przedstawiono wyniki badań utleniania stopu Ti-25Al-12Nb rozpatrując wpływ chropowatości powierzchni. Utlenianie przeprowadzono w atmosferze powietrza o temperaturze 800ºC. Stwierdzono, iż wzrost chropowatości powierzchni sprzyja zwiększeniu odporności na utlenianie. W pracy scharakteryzowano strukturę geometryczną powierzchni oraz adhezyjność powstających warstw tlenkowych.

15

Mössbauer study of treated Nd2Fe14B

Budzyński M., Constantin V. C., Popescu A.-N. J., Surowiec Z., Tkachenka T. M., Yanushkevich K. I.

Nukleonika

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2015

|

Vol. 60, No. 1

7--10

EN

The Nd2Fe14B cylindrical magnets were treated with water solutions of alkali, acid, and salt. Mössbauer spectroscopy was applied to study the composition and properties of the surface material of the treated magnets. It is shown that the main phase of the permanent Nd2Fe14B magnet partly decomposes. The released α-Nd at the grain boundaries interacts with water and forms neodymium hydroxide matrix, and the released Fe diffuses into it. The presence of Fe-Nd(OH)3 is refl ected in the paramagnet doublet in the Mössbauer spectra of treated neodymium magnets.

16

Non-conventional processing routes and applications of intermetallics

Novak P.

Mechanik

|

2015

|

R. 88, nr 2CD

93--99

EN

Intermetallics are materials offering wide variety of interesting properties, such as high hardness, high chemical resistance, shape memory or hydrogen storage ability. However, the synthesis and processing of intermetallic compounds by common metallurgical techniques is often very problematic. In this paper, the modern techniques involving non-conventional processes of powder metallurgy, reactive sintering and mechanical alloying, are presented. In the field of application, novel directions are linked – the use of intermetallic-based materials as surgical implants or tool materials.

PL

Materiały na osnowie faz intermetalicznych oferują szeroką gamę interesujących właściwości, takich jak wysoka twardość, wysoka odporność chemiczna, pamięć kształtu i zdolność do przechowywania wodoru. Jednakże synteza i wytwarzanie związków międzymetalicznych zwykłymi technikami metalurgicznymi jest często bardzo problematyczna. W niniejszej pracy zaprezentowano nowoczesne techniki obejmujące niekonwencjonalne procesy metalurgii proszków, spiekania reaktywnego i mechanicznego stopowania Wskazano nowe zastosowania materiałów na osnowie faz intermetalicznych, takie jak implanty chirurgiczne czy materiały narzędziowe.

17

First-principle investigations of structural and electronic properties of TMAl (TM = Fe, Co, and Ni) transition metal aluminides

Bendouma D, Allel M., Mustapha I. B., Miloud B., Abdelkader T.

Materials Science Poland

|

2015

|

Vol. 33, No. 2

251--258

EN

In the present work, we have investigated the structural and electronic properties of TMAl (TM = Fe, Co, and Ni) transition metal aluminides in the B2 structure, using first-principle calculations of the density functional theory (DFT) based on the linearized augmented plane wave method (FP-LAPW) as implemented in the WIEN2k code, in which the energy of exchange and correlation are treated by the generalized gradient approximation (GGA), proposed in 1996 by Perdew, Burke and Ernzerhof (PBE). The ground state properties have been calculated and compared with other calculations, and the electronic structures of all FeAl, CoAl, and NiAl compounds exhibited a metallic behavior. It was depicted that the density of states is characterized by the large hybridization between the s-p (Al) and 3d (Fe, Co, and Ni) states, which creates the pseudogap in the region of anti-bonding states. Moreover, the band structures of FeAl, CoAl, and NiAl are similar to each other and the difference between them is in the energy level of each band relative to the Fermi level.

18

Three Dimensional Morphology of β-Al5FeSi Intermetallics in AlSi Alloys

Mikołajczak P., Ratke L.

Archives of Foundry Engineering

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2015

|

Vol. 15, iss. 1

47--50

EN

Iron is the most common and detrimental impurity in casting alloys and has been associated with many defects. The main consequence of the presence or adding of iron to AlSi alloys is the formation Fe-rich intermetallics with especially deleterious β-Al5FeSi. β-Al5FeSi phases are most often called needles on 2D micro sections, whilst platelets in 3D geometry. The x-ray tomography results have demonstrated Fe-rich phases with shapes different from simple forms such as needles or platelets and presented bent and branched phases. β grown as complicated structure of bent and branched intermetallics can decrease feeding ability, strengthen pores nucleation and eutectic colonies nucleation leading to lower permeability of mushy zone and porosity in the castings.

19

Fe40Al intermetallic samples sintered by pressure-assisted induction sintering (PAIS) method

Siemiaszko D., Mościcki R.

Inżynieria Materiałowa

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2014

|

Vol. 35, nr 2

191--193

EN

The paper presents the results of sintered Fe40Al received inductive method PAIS (pressure-assisted sintering induction). The starting material was a mixture of elemental powders of Fe + 40 at. Al. The powder mixture was placed in a graphite die and pressed by graphite punches. The diameter of the sample was 50 mm and a height of 8 mm. The consolidation process was carried out using a inductive sintering device (PAIS) developed at the Department of Advanced Materials and Technology, Military Technical Academy. Sintering procedure was performed in a vacuum chamber (pressure of 2 mbar) using a pressing pressure of 60 MPa. Heating the samples was performed using three different power ranges 16 kW, 20 kW and 25 kW. The temperature was controlled with two devices: a pyrometer that measures the surface temperature of the die and a thermocouple placed at the axis of the sample approximately 1 mm from the surface. The studies showed that the difference between pyrometer and thermocouple is approximately 100°C. This effect is results from the specificity of induction heating where first the die is heat up then the sample situated in the middle. Heating velocity calculations performed have shown that it is respectively 75°C/min for a 16 kW, 150°C/min to 20 kW and 220°C/min for 25 kW. Sintered densities were tested (including open and closed porosity) also Vickers hardness (HV10), phase composition by X-ray diffraction (XRD) and microstructure were observed with a scanning electron microscope (SEM) analysis of the chemical composition (EDS).

PL

W pracy zaprezentowano wyniki badań spieków Fe40Al otrzymanych metodą indukcyjną PAIS (pressure-assisted induction sintering). Materiałem wyjściowym była mieszanina proszków elementarnych Fe + 40 at. Al. Mieszaninę proszku umieszczano w grafitowej matrycy i dociskano za pomocą grafitowych stempli. Średnica próbki wynosiła 50 mm, a wysokość 8 mm. Proces konsolidacji prowadzono za pomocą urządzenia do spiekania indukcyjnego (PAIS) opracowanego w Katedrze Zaawansowanych Materiałów i Technologii Wojskowej Akademii Technicznej. Spiekanie prowadzono w komorze próżniowej (ciśnienie 2·102 Pa) stosując ciśnienie prasowania 60 MPa. Nagrzewanie próbek wykonano stosując trzy różne moce grzania 16 kW, 20 kW i 25 kW. Temperatura kontrolowana była dwoma urządzeniami: pirometrem mierzącym temperaturę na powierzchni matrycy i termoparą umieszczoną w osi próbki ok. 1 mm od jej powierzchni. Przeprowadzone badania wykazały, że różnica wskazań pirometru i termopary wynosi ok. 100°C. Efekt ten wynika ze specyfiki grzania indukcyjnego, podczas którego w pierwszej kolejności nagrzewała się najbliżej położona matryca, a następnie, położona w środku próbka. Przeprowadzone obliczenia prędkości nagrzewania wykazały, że wynosi ona odpowiednio: 75°C/min dla 16kW, 150°C/min dla 20kW i 220°C/min dla 25kW. Spieki poddano badaniu gęstości (w tym także porowatości otwartej i zamkniętej), twardości sposobem Vickersa (HV10), badania składu fazowego metodą dyfrakcji rentgenowskiej (XRD) oraz poddano obserwacji mikrostruktury za pomocą skaningowego mikroskopu elektronowego (SEM) z analizą składu chemicznego (EDS).

20

Oxidation Resistance of Alcrn Coating Deposited on Ti-46Al-7Nb-0.7Cr-0.1Si-0.2Ni Alloy

Małecka J.

Archives of Metallurgy and Materials

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2014

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Vol. 59, iss. 2

621--627

EN

This article presents the results of research on resistance to isothermal oxidation of Ti-46Al-7Nb-0,7Cr-0,1Si-0,2Ni alloy with AlCrN layer applied. The reference material was a Ti-46Al-7Nb-0,7Cr-0,1Si-0,2Ni alloy in initial state without any coating deposited. The protective coating was deposited by PVD process. Attempts at isothermal oxidation in air were performed at 900 and 950°C during 250h. Measurements of the samples’ mass were taken with the accuracy of 10-4 g. An analysis of the obtained results was made: chemical composition analysis, phase analysis of the deposited coating and chemical composition analysis of the alloy surface with the coating deposited after oxidation tests. In the case of the oxidation of alloy in initial state, pronouncedly higher mass gain and ”deferred” scale chipping was noticed. The deposited AlCrN coating significantly reduces spalling processes and makes for lesser mass gain of the oxidized alloy.

PL

W artykule przedstawiono wyniki badań odporności na utlenianie izotermiczne stopu Ti-46Al-7Nb-0.7Cr-0.1 Si-0.2Ni z naniesioną powloką AICrN. Materiałem referencyjnym był stop Ti-46Al-7Nb-0.7Cr-0.1 Si-0.2Ni w stanie wyjściowym, bez naniesionej powłoki. Powłoka ochronna naniesiona została w procesie PVD. Próby izotermicznego utleniania w powietrzu przeprowadzono w temperaturze 900 i 950°C w czasie 250h. Pomiary masy próbek przeprowadzane były z dokładnością 10-4 g. Dokonano analizy uzyskanych wyników: składu chemicznego i fazowego naniesionej powłoki oraz składu chemicznego powierzchni stopu z naniesioną powłoką po testach utleniania. Stwierdzono, w przypadku utleniania stopu w stanie wyjściowym, wyraźnie większe przyrosty masy i „zwłoczne” odpryskiwanie zgorzeliny. Naniesiona powłoka AICrN zdecydowanie ograniczyła procesy odpryskiwania zgorzeliny oraz przyczyniła się do mniejszego przyrostu masy utlenianego stopu.