Ti-Ni-V形状记忆合金及其弹簧的相变和形变特性

用X射线衍射仪、示差扫描量热仪和拉伸实验研究了退火温度Tan和形变温度Td对Ti-50.8Ni-0.5V形状记忆合金丝及其弹簧的相变和形变特性的影响。结果表明:400～600℃退火态合金的室温相组成为B2和R相。冷却/加热时,350～400℃退火态合金发生A→R/R→A(A—母相,R—R相)一阶段可逆相变;450～500℃退火态合金发生A→R→M/M→R→A(M—马氏体相)两阶段可逆相变;550℃退火态合金发生A→R→M/M→A型相变;600℃退火态合金发生A→M/M→A一阶段可逆相变。随Tan升高,R相变温度先升高后降低,M相变温度先升高后趋于稳定,M相变热滞快速降低,而R相变热滞则几乎不受退火温度影响。随Td和Tan升高,退火态Ti-50.8Ni-0.5V合金弹簧的应力诱发M临界切应力升高。

Transformation and deformation characteristics of TiNiV shape memory alloy and spring

Effects of annealing temperature(Tan) and deforming temperature(Td) on the transformation and deformation characteristics of Ti-50.8Ni-0.5V(atomic fraction,%) shape memory alloy wire and coil spring were investigated by means of X-ray diffraction,differential scanning calorimetry and tensile test.The main phases of the alloy annealed at temperatures of 400-600 ℃ are parent phase(B2) and R phase at room temperature.The A→R/R→A(A-parent phase,R-R phase) type one-stage reversible transformation occurs in the alloy annealed at 350-400 ℃,the A→R→M/M→R→A(M-martensite phase) type two-stage transformation occurs when the alloy is annealed at 450-500 ℃,the A→R→M/M→A type transformation occurs in 550 ℃ annealed alloy,and A→M/M→A type transformation occurs in the alloy annealed at 600 ℃ upon cooling/heating.With increasing Tan,the R transformation temperature increases initially and then decreases,the M transformation temperature increases first and then tends to be stable,the M transformation temperature hystersis decreases and the R transformation temperature hystersis is hardly affected by Tan.With the increase of Tan and Td,the critical shear stress for stress-induced martensitic transformation of the Ti-50.8Ni-0.5V alloy spring increases.