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1

Elastic Constants by Resonant Ultrasound Spectroscopy – Application to Thermoelectrics and Aluminum Alloys

Klobes Benedikt

Scientific Journal of Gdynia Maritime University

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2019

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nr 112

60--68

EN

Resonant ultrasound spectroscopy is a non-destructive technique for determining the elastic constants of a material. In the context of thermoelectric materials, elastic constants can be used to investigate the speed of sound and, thus, the lattice thermal conductivity of a substance. For Mg2Si-Mg2Sn solid solutions, a possible connection between shear modulus and band convergence can be assumed in that way. Moreover, the rather low speed of sound in this system points towards a high contribution of optical phonons to thermal conductivity. Additionally, significant resonance frequency shifts are observed during natural aging of technical Al-Cu-Mg and Al-Mg-Si alloys, which are proposed to assist investigation of the early stages of clustering in the future.

2

Aging kinetics and mechanical properties of copper-bearing low-carbon HSLA-100 microalloyed steel

Sohrabi M. J., Mirzadeh H., Mehranpour M. S., Heydarinia A., Razi R.

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 4

1409--1418

EN

The precipitation kinetics of HSLA-100 steel and the correlation between tensile and impact properties were studied. According to the modified Johnson–Mehl–Avrami–Kolmogorov (JMAK) analysis and based on the analysis of the time corresponding to the transformed fraction of 0.5 (t0.5), the activation energy for the precipitation of copper during aging of martensite was determined as ~111 and 105 kJ/mol, respectively. These values are much smaller than the activation energy for the diffusion of Cu in a-iron, which was related to the effect of high dislocation density of the quenched martensitic microstructure on the aging process. These results were verified based on the diffusional calculations. Based on the analysis of mechanical behavior, no reasonable correlation was found between strength of the material and the impact energy. However, the impact energy was found to be propor-tional to the UTS-YS, where the latter is an indicator of the work-hardening capability of the material. This revealed that the work-hardening capacity of the material is a much more important factor for determining the impact toughness compared to its strength.

3

Impact of the type of quench aging after hyperquenching on the mechanical strength properties of AW-7020 alloy

Hajdukiewicz G.

Journal of KONES

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2018

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Vol. 25, No. 2

141--148

EN

The article attempts to determine the influence of selected types of the heat treatment on the strength properties of the AW-7020 alloy used in the shipbuilding industry. The text presents information on the applied types of heat treatment. There are presented the results of the static tensile test of the material after its earlier hyperquenching and aging (natural and artificial) as well as comparison to the test results of the alloy without heat treatment. To illustrate the nature of the supersaturation and aging process, a test was carried out for a series of samples in a transitional state. During the tests for all the samples were determined: elongation at rupture and reduction of area at fracture, strength limit Rm and proof stress Re0.2. The results of the tests showed that the choice of the type of aging after saturation has significant importance for the strength properties of the AW-7020 alloy. It has been shown that it is possible to significantly accelerate the achievement of higher strength properties of the tested alloy, replacing the natural aging of the material with artificial aging.

4

Impact of rotary swaging and age hardening on mechanical properties of EN AW 2024

Kövér M., Sláma P., Palán J.

Journal of Achievements in Materials and Manufacturing Engineering

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2015

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Vol. 72, nr 2

61--66

EN

Purpose: Invention of severe plastic deformation methods led to increased interest in ultra-fine grained materials. The hardenable aluminium alloys were extensively studied in the last decade. It was revealed that combination of severe plastic deformation and age hardening can significantly improve the material properties of these alloys. In this article we performed such progressive thermo-mechanical treatment and following mechanical testing and metallographic analysis. The aim was to evaluate the influence of this treatment on mechanical properties, mostly the effect of various age hardening temperatures and time. Aluminium alloy EN AW 2024 was chosen for the experimental procedures. Impact of processing parameters on mechanical properties was determined by tensile testing. Metallographic analysis was used for evaluation of the straining influence on grain morphology. In the conclusion we denoted significant strain hardening effect, present shear bands and change in aging kinetics. Design/methodology/approach: The experimental material was processed by progressive thermo-mechanical treatment. The evaluation was performed by simple tensile testing and light microscopy. The first conclusions were derived from determined mechanical properties and based on similarities in available publications with related topic. Findings: The research results roughly confirm the recovery-precipitation complementary effect, observed in other hardenable aluminium alloys or the same hardenable alloy deformed by other SPD technique. The impact of both parts of processing – deformation and age hardening on mechanical properties was evaluated. Research limitations/implications: Future detailed investigation of secondary phase particles and dislocation-precipitate interaction should be performed. This investigation was not performed as it requires transmission electron microscopy. Originality/value: The paper contains first impression on promising SPD technique. As the technique appeared only recently, very few articles were published, considering few light alloys. The paper can help to set parameters for other researchers in this field and promote commercialization of this progressive thermo-mechanical processing

5

Phase Transformation And Mechanical Properties Of Ti-12.1Mo-1Fe Alloy With Nano-Sized Precipitation

Lee D.-G., Seo J., Li Ch., Lee Y.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 2B

1393--1396

EN

Microstructural characterization and aging hardening behaviors of a new designed Ti-12.1Mo-1Fe alloy during solution treatment and aging were investigated in the present study. It is well known that when β-Ti alloys are generally under solution treatment or aging, α phases and ω phases appear or disappear dependent on heat treatment temperature and holding time. It is very necessary to understand the phase transformation phenomenon and to control the microstructure because these phases can control the drastic changes of the mechanical and physical properties of these alloys. According to the calculated [Mo]eq value and the microstructural observation, the β-transus temperature was about 780°. After the solution treatment, this alloy was composed of the β-phase and the microstructure mainly consisted of the equiaxed β grains with the average size of 25 μm. ω phases which were precipitated during aging process, played a more important role to the hardening effect than α phases. The highest hardness value of Ti-12.1Mo-1Fe alloy showed in the condition of the aging temperature of 450°. The hardening due to ω-phase precipitation can lead to a high hardness about 480 Hv but the coarse α-phase result in hardness below 300 Hv.

6

Effects Of T6 Heat Treatment With Double Solution Treatment On Microstructure, Hardness And Corrosion Resistance Of Cast Al-Si-Cu Alloy

Wiengmoon A., Sukchot P., Tareelap N., Pearce J. T. H., Chairuangsri T.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 2A

881--886

EN

Effects of T6 heat treatment with double solution treatment on microstructure, hardness and corrosion resistance of a cast A319 (Al-4.93wt%Si-3.47wt%Cu) alloy were investigated. The T6 heat treatment comprised of the first solution treatment at 500±5°C for 8 h, the second solution treatment in the temperature range of 510 to 530±5°C for 2 h followed by water quenching (80°C), and artificial aging at 170°C for 24 h followed by water quenching (80°C). Microstructure of the alloy was studied by optical microscopy and electron microscopy, Rockwell hardness was measured, and corrosion resistance in 0.1 M NaCl aqueous solution was determined by a potentiodynamic technique. The results revealed that the T6 heat treatment with double solution treatment led to an improvement in corrosion resistance and comparable macrohardness as compared to those obtained from the case of single solution treatment. The second solution treatment at 520°C is the optimum leading to relatively low corrosion current density without substantial drawbacks on breakdown potential or the width of passive range.

PL

W pracy badano wpływ obróbki termicznej T6 połączonej z podwójnym przesycaniem na mikrostrukturę, twardość oraz odporność na korozję stopu A316 (Al-4,93Si-3,47Cu w % wag.) otrzymanego metodą odlewania. Obróbkę termiczną T6 przeprowadzono w następujący sposób: w pierwszej kolejności stop poddano przesycaniu w temperaturze 500±5°C przez 8 godzin, a następnie w zakresie temperatur od 510 do 530±5°C przez 2 godziny, hartowanie wodą (80°C) oraz sztuczne starzenie w 170°C przez 24 godziny i ponowne hartowanie wodą (80°C). Mikrostrukturę stopu badano metodami mikroskopii optycznej i mikroskopii elektronowej. Pomiar twardości stopu wykonano metodą Rockwella. Odporność stopu na korozję w roztworze wodnym 0.1 M NaCl wyznaczono metodą potencjodynamiczną. Otrzymane wyniki wykazały, że obróbka termiczna T6 z podwójnym przesycaniem prowadzi do poprawy makrotwardości oraz odporności materiału na korozję w porównaniu do stopu poddanego pojedynczemu przesycaniu. Stwierdzono także, iż drugie przesycanie w temperaturze 520°C jest optymalne i prowadzi do stosunkowo niskiej gęstości prądu korozyjnego bez znaczących odchyleń potencjału rozkładowego lub szerokości zakresu pasywnego.

7

Precipitation strengthening of ultrafine-grained Al-Mg-Si alloy processed by hydrostatic extrusion

Chrominski W., Kulczyk M., Lewandowska M., Kurzydlowski K. J.

Zeszyty Historyczne Politechniki Warszawskiej

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2014

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z. 16

77--84

EN

Precipitation strengthening of an ultrafine-grained Al-Mg-Si alloy has been studied using samples obtained by hydrostatic extrusion. It has been demonstrated that the microstructure after hydrostatic extrusion consists of two types of grains: (1) nano-sized free of dislocations and surrounded with high angle grain boundaries and (2) micron-sized with dislocation substructure. After ageing at 160C, small needle-like precipitates appear in grain interiors of both nano- and micron-sized grains, bringing about a significant strength improvement. However, the precipitates are smaller than those in their coarse grained counterparts. As a consequence, they constitute weaker barriers for dislocations and induce a lower strengthening effect. In addition, one may observe intensive precipitation at nano-grains boundaries, which further reduces the strengthening effect. It was also shown that peak ageing and overageing take place for much shorter time than in the case of coarse grained samples and are caused by the grain growth rather than a change in the precipitation state.

8

Influence the heat treatment of two base metal alloys used on dental prosthesis on corrosion resistance

Reimann Ł., Dobrzański L.A., Nieradka B., Kusy M., Riedlmajer R.

Journal of Achievements in Materials and Manufacturing Engineering

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2013

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Vol. 57, nr 2

83--90

EN

Purpose: The goal of the study is to try find the influence of the heat treatment on the corrosion resistance of two base cobalt alloys used on dental prosthesis. Design/methodology/approach: The investigation was choosen two base cobalt alloys: Remanium 2000+ (Dentaurum) and Wirobond LFC (Bego). Corrosion resistance test were carried out at room temperature and use of the Potentiostat IPS AJ PGU system for electrochemical tests. The examination use of water center which simulated artificial saliva environment. The evaluation of pitting corrosion was realized by recording of anodic polarization curves with use the potentiodynamic methods. Structure observation was made after surface preparation by light microscope. Findings: Research cobalt alloys are characterized by a dendritic crystals in structure. For both cobalt alloys increasing the time of age hardening effect on growth of the corrosion resistance, especially to increase the potential for pitting initiation. Research limitations/implications: The research was carried out on samples, not on final elements. Practical implications: The research material is used on dentures, so it must characterize the corrosion resistance. Results of this work make up an information on what heat treatment parameters may be pay attention for two base cobalt alloys: Remanium 2000+ (Dentaurum) and Wirobond LFC (Bego). Originality/value: The paper presents influence the heat treatment of two base metal alloys used on dental prosthesis on corrosion resistance.

9

Effect of age hardening on corrosion resistance and hardness of CoCrMo alloys used in dental engineering

Dobrzański L., Reimann Ł., Krawczyk C.

Archives of Materials Science and Engineering

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2012

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Vol. 57, nr 1

5-12

EN

Purpose: The goal of the study is to research the effect of various time of ageing on corrosion resistance, hardness and structures of Remanium 2000+ Co-Cr-Mo alloys used in prosthodontia. Design/methodology/approach: To investigation was prepared mould, cast in 1430°C and realized the heat treatment: solutioning in 1250°C by 3 hours and then ageing in 850°C by 4, 8, 16 and 24 hours. Electrochemical corrosion examination were made in water center which simulated artificial saliva environment. The evaluation of breakdown potential was realized by recording of anodic polarization curves with use the potentiodynamic methods. Corrosion resistance test were carried out at room temperature and use of the VoltaLabŽ PGP201 system for electrochemical tests. Hardness test were obtained by use the microhardness FM ARS 9000 FUTURE TECH with load 1 kg. Structure observation was made after surface preparation: grinding, polishing and etching by light microscope LEICA MEF4A with the magnification 500x. Findings: The age hardening for Co-Cr-Mo alloys is one of the possible method which effect in forming the hardness. The highest value of hardness were obtain for specimen which was ageing with the longer time. Research alloy characterized dendritic crystals in structure for all realized heat treated process. At specimen after the longer ageing was observed the most of discontinuous precipitation and stacking faults in compare with specimen ageing by 4 hours. The age hardening doesn’t influenced much on electrochemical results and only the open circuit potential changed by decreased while increased ageing time. The values of breakdown potential and repassivation potential kept at a constant level. Practical implications: Research material is used on dentures so it’s demand that their characterized corrosion resistance and result of this work make up an information on what heat treatment parameters may be pay attention for CoCrMo alloys. Originality/value: The paper present effect of age hardening especially the ageing time, on the most important criteria of CoCrMo alloys use in dental engineering.

10

Identification and Analysis of Intermetallic Phases in Age-Hardened Recycled AlSi9Cu3 Cast Alloy

Hurtalová L., Tillová E., Chalupová M.

Archive of Mechanical Engineering

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2012

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Vol. LIX, nr 4

385--396

EN

Purpose: The influence of age-hardening solution treatment at temperature 515 degrees centigrade with holding time 4 hours, water quenching at 40 degrees centigrade and artificial aging by different temperature 130, 150, 170 and 210 degrees centigrade with different holding time 2, 4, 8, 16 and 32 hours on changes in morphology of Fe-rich Al15(FeMn)3Si2 and Cu-rich (Al2Cu, Al-Al2Cu-Si) intermetallic phases in recycled AlSi9Cu3 cast alloy. Material/Methods: Recycled (secondary) AlSi9Cu3 cast alloy is used especially in automotive industry (dynamic exposed cast, engine parts, cylinder heads, pistons and so on). Microstructure was observed using a combination of different analytical techniques (scanning electron microscopy upon standard and deep etching and energy dispersive X-ray analysis – EDX) which have been used for the identification of the various phases. Quantitative study of changes in morphology of phases was carried out using Image Analyzer software NIS-Elements. The mechanical properties (Brinell hardness and tensile strength) were measured in line with STN EN ISO. Results/Conclusion: Age-hardening led to changes in microstructure include the spheroidization of eutectic silicon, gradual disintegration, shortening and thinning of Fe-rich intermetallic phases and Al-Al2Cu-Si phases were fragmented, dissolved and redistributed within alpha-matrix. These changes led to increase in the hardness and tensile strength in the alloy.

PL

Cel: Badanie wpływu utwardzania przez starzenie przesycanie w temperaturze 515 stopni Celsjusza z czasem przetrzymywania 4 godz., hartowanie wodne w 40 stopniach Celsjusza, starzenie przyspieszone w różnych temperaturach: 130, 150, 170 i 210 stopni Celsjusza, przy czasach przetrzymywania: 2, 4, 8, 16 i 32 godziny na zmiany w morfologii stopów odlewniczych AlSi9Cu3 z recyklingu wzbogaconych żelazem (Al15(FeMn)3Si2) lub miedzią (Al2Cu, Al-Al2Cu-Si). Materiał i metody: Pochodzący z recyklingu (wtórny) stop odlewniczy aluminium AlSi9Cu3 jest powszechnie używany, zwłaszcza w przemyśle motoryzacyjnym (dynamiczne, odkryte odlewy, części silnika, głowice cylindrów, tłoki itp.). Mikrostrukturę odlewów badano stosując kombinację różnych technik analitycznych (elektronowa mikroskopia skaningowa w połączeniu z analizą rentgenowską z dyspersją energii (EDX), standardową i z głebokim wytrawianiem), co pozwoliło identyfikować różne fazy międzymetaliczne. Ocena ilościowa zmian w morfologii tych faz została przeprowadzona przy wykorzystaniu oprogramowania analizatora obrazów (Image Analyzer NIS-Elements). Właściwości mechaniczne (twardość w skali Brinella i wytrzymałość na rozciaganie) były mierzone zgodnie z normą STN EN ISO. Wyniki i wnioski: Utwardzanie przez starzenie prowadzi do zmian w mikrostrukturze, które polegają na sferoidyzacji krzemu eutektycznego, stopniowej dezintegracji, skracaniu i ścienianiu faz międzymetalicznych wzbogaconych żelazem. Fazy Al-Al2Cu-Si podlegały fragmentacji, zostały rozpuszczone i redystrybuowane w osnowie stopu. Zmiany te prowadzą do wzrostu twardości stopu i jego wytrzymałości na rozciąganie.

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Teoretické aspekty tepelného spracovania zlievarenských hliníkových zliatin

Schützová D., Lenárthová J., Bobok L'., Lukáč I.

Archiwum Odlewnictwa

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2006

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R. 6, nr 18/1

143--148

CS

Mechanické vlastnosti odliatkov významne ovplyvňuje veľkosť dendritických buniek, prítomnosť metalurgických chýb, (napr. dendritická pórovitosť), podiel, veľkosť a kryštalografická orientácia intermetalických zlúčenín, ako aj procesy tepelného spracovania. V príspevku je naznačená teoretická podstata tepelného spracovania hliníkových zliatin.

EN

The paper aims is to point out on the theoretical principles of the heat treating of the Aluminium Alloys. The following major parameters have significant effects on the mechanical properties of the casting products: 1. Size of the dendrite cells. 2. Presence of the metallurgical faults, i.e. dendrite porosity. 3. Fraction, size and crystallographic orientation of intermetallic compounds. 4. Heat treating processes.