Investigating microstructural evolution during homogenization of the equiatomic NiTi shape memory alloy produced by vacuum arc remelting

Foroozmehr, A.; Kermanpur, A.; Ashrafizadeh, F.; Kabiri, Yoones

doi:10.1016/j.msea.2011.07.024

“…Ti 3 Ni 4 , Ti 2 Ni 3 and TiNi 3 are three dominate phases in the microstructure depending upon the aging temperature and time. Ti 3 Ni 4 , TiNi 3 , Ti 3 Ni 4 are formed at lower aging temperatures (< 600 °C) and shorter aging time, at higher aging temperature and longer aging time and at intermediate temperature and time, respectively [19]. There is unfavorable phase that is Ti 2 Ni, presents in the ascast materials produced by VIM.…”

Section: Introductionmentioning

confidence: 99%

Effect of Aging Heat Treatment on Microstructure and Mechanical Properties of 50 wt.% Ni-42.5 wt.% Ti-7.5 wt.% Cu Shape Memory Alloy

Omrani¹,

Shokuhfar²

2019

Int J Metall Met Phys

0

1

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NiTi alloys have good shape memory properties that adding alloying elements such as Cu can help to have smaller temperature hysteresis, better thermoelasticity, smaller superelastic hysteresis, higher damping capacity, and superior fatigue properties. The present work addresses functional mechanical properties of 50 wt.% Ni-42.5 wt.% Ti-7.5 wt.%. We study how aging heat treatment affects the alloy microstructure and mechanical properties. The results exhibit that increasing the aging temperature tend to increase the size of precipitation due to high diffusion in high temperature. The evaluation of mechanical properties reveals that the samples that aged in high temperature has lower fracture strength while these samples shows higher fracture strain. Aging time also has an effect on properties where by increasing the time, the size and amount of precipitations increase due to sufficient time for diffusion. By increasing the time, the fracture strength increase until a critical point and after that the fracture strength reduces.

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“…An alternative vacuum melting technology is called vacuum arc remelting (VAR) (5). In this process, the metal is melted via an induction unit and poured into the mold under vacuum.…”

Section: Vacuum Casting Furnace Typesmentioning

confidence: 99%

Advanced Casting Methodologies

Kapranos

¹

,

Brabazon

²

,

Midson³

et al. 2014

Comprehensive Materials Processing

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“…Thermoelastic martensitic transformation from high temperature austenite phase (B2) to low temperature martensite phase (B19') tends to gain shape memory and superelasticity behavior [9][10][11][12][13][14][15][16][17][18]. There is limited application for specific field where martensitic transformation temperatures around or below the room temperature [19]. By increasing the transformation temperature give more opportunity to employ these alloys in automotive and electro-technique industries [15].…”

Section: Introductionmentioning

confidence: 99%

Untitled

2019

Int J Metall Met Phys

0

View full text Add to dashboard Cite

NiTi alloys have good shape memory properties that adding alloying elements such as Cu can help to have smaller temperature hysteresis, better thermoelasticity, smaller superelastic hysteresis, higher damping capacity, and superior fatigue properties. The present work addresses functional mechanical properties of 50 wt.% Ni-42.5 wt.% Ti-7.5 wt.%. We study how aging heat treatment affects the alloy microstructure and mechanical properties. The results exhibit that increasing the aging temperature tend to increase the size of precipitation due to high diffusion in high temperature. The evaluation of mechanical properties reveals that the samples that aged in high temperature has lower fracture strength while these samples shows higher fracture strain. Aging time also has an effect on properties where by increasing the time, the size and amount of precipitations increase due to sufficient time for diffusion. By increasing the time, the fracture strength increase until a critical point and after that the fracture strength reduces.

show abstract

Investigating microstructural evolution during homogenization of the equiatomic NiTi shape memory alloy produced by vacuum arc remelting

Cited by 37 publications

References 21 publications

Effect of Aging Heat Treatment on Microstructure and Mechanical Properties of 50 wt.% Ni-42.5 wt.% Ti-7.5 wt.% Cu Shape Memory Alloy

Effect of Aging Heat Treatment on Microstructure and Mechanical Properties of 50 wt.% Ni-42.5 wt.% Ti-7.5 wt.% Cu Shape Memory Alloy

Advanced Casting Methodologies

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