The effect of vanadium on structure and martensitic transformation temperature of TiPt alloy

Conference of the South African Advanced Materials Initiative 2018

Chikosha, S.^1 ; Mahlatji, M.L.^1 ; Modiba, R.^1 ; Chikwanda, H.K.^1

Light Metals, Materials Science and Manufacturing, Council for Scientific and Industrial Research (CSIR), Meiring Naudé, South Africa^1

关键词: Energy dispersive X ray spectroscopy;    First-principles approaches;    First-principles study;    High temperature shape memory alloy;    Martensitic transformation temperatures;    Solid solution strengthening;    Three phase microstructure;    Transformation temperatures;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/430/1/012022/pdf
DOI  :  10.1088/1757-899X/430/1/012022

来源: IOP

【 摘 要 】

Shape memory alloys find application as sensors, microcontrollers or actuators. The TiPt binary system, a potential high temperature shape memory alloy due to its high transformation temperature of approximately 1000°C, displays negligible work output. This makes it unsuitable for actuator applications where work output is a prerequisite. A necessary condition for sufficient work output is for the alloy to display a critical stress for slip in austenite phase greater than detwinning stress of martensite phase. Solid solution strengthening, work hardening and precipitation hardening are possible mechanisms to improve work output. An indirect consequence of solid solution strengthening is altering of the crystal structure and the transformation temperature. This study evaluates the effect of partial substitution of Pt with V to form ternary Ti50Pt43.75V6.25 (at.%) on the above-mentioned properties. Phase analysis and identification was done using scanning electron microscopy with energy-dispersive X-Ray spectroscopy and X-Ray diffraction. The transformation temperatures were studied by differential scanning calorimetry. Results show a three-phase microstructure with B19 Ti50(PtV)50 martensite as the major phase. The transformation temperature reduced with addition of vanadium in agreement with the predicted results from first-principles approach. However, the experimentally observed B19 structure did not agree with first-principles studies at 0K where B19' was the predicted stable phase.