Phase Transformations and Super-Elasticity of a Ni-rich TiNi Alloy with Ultrafine-Grained Structure
A Ni-rich Ti-50.7.at%Ni alloy was processed by Equal Channel Angular Extrusion (ECAE) at 500℃. After 8 passes ECAE, microstructure was refined to sub-micron scale, approximately 0.2 um~0.3 urn. TEM observation reveals that Ti3Ni4 phase precipitated in Ni-rich Ti-50.7.at%Ni alloy during the preheating treatment before each ECAE pass, but re-dissolved during sequent ECAE processes. After ECAE treatment, the B2→R transformation occurred within a larger temperature range. Comparing with the solution-treated TiNi specimen, the martensitic transformations start (Ms) and peak temperatures (Mp) of TiNi specimens ECAEed were dramatically lowered. Super-elasticity characteristics of TiNi alloy were tested by tensile loading and unloading cycles. The results reveal that at a tensile strain of 4% or smaller, ultrafinegrained (UFG) TiNi alloy processed by 4 passes ECAE shows better super-elasticity than solution-treated sample. Microstructure evolution and its effect on phase transformations and super-elasticity characteristics have been discussed.
Zhiguo Fan Jie Song Xiaoning Zhang Chaoying Xie
State Key Lab.Of Metal Matrix Composites,School of Materials Science and Engineering,Shanghai Jiao Tong University,Shanghai 200240,China
国际会议
5th International Conference on Nanomaterials by Severe Plastic Deformation(第五届剧烈塑性变形纳米材料国际会议)
南京
英文
1137-1142
2011-03-01（万方平台首次上网日期，不代表论文的发表时间）