【摘要】 使用示差扫描量热仪(DSC)和拉伸实验研究了Cr掺杂对550℃退火态Ti-50.8Ni(原了分数,%)形状记忆合金相变和循环形变特性的影响.结果表明,Ti-50.8Ni合金冷却/加热时发生B2→R→M/M→B2型可逆相变,掺杂0.3%Cr后所得Ti-50.8Ni-0.3Cr合金的相变类型为B2→R→M/M→R→B2,相变温度大幅度降低.室温下,Ti-50.8Ni和Ti-50.8Ni0.3Cr合金的相组成均为母相B2,前者呈现形状记忆效应,后者呈现超弹性.随循环变形次数n的增加,Ti-50.8Ni合金的特性由形状记忆效应演变为线性超弹性,合金的应力诱发马氏体临界应力和积累残余应变迅速增加;Ti-50.8Ni-0.3Cr合金的特性由非完全超弹性演变为完全超弹性,超弹性应力-应变曲线形态比较稳定.随n增加,Ti-50.8Ni合金的超弹性残余应变ε_r减小,超弹性应变恢复率η_s增加;Ti-50.8Ni-0.3Cr合金的ε_r和η_s则分别稳定在较低和较高水平,超弹性稳定.更多还原

【Abstract】 The effect of Cr addition on the transformation and the cyclic deformation characteristics in 550℃annealed Ti-50.8Ni shape memory alloy(SMA) were investigated by differential scanning calorimetry(DSC) and tensile test.The B2→R→M/M→B2 type reversiable transformation occurred in Ti-50.8Ni alloy upon cooling/heating.After the addition of 0.3%Cr in Ti-50.8Ni alloy the transformation type for Ti-50.8Ni-0.3Cr alloy was B2→R→M/M→R→B2,and the transformation temperatures decreased significantly.At room temperature,the phase composition was parent phase B2 for both Ti-50.8Ni and Ti-50.8Ni-0.3Cr alloys,while the former showed shape memory effect;the latter showed superelasticity.With increasing cyclic deformation number n,Ti-50.8Ni alloy evolved from shape memory effect to linear superelasticity,and its stress inducing martensitic critical stress and the accumulation residual strain increased rapidly;while Ti-50.8Ni-0.3Cr alloy evolved from incomplete superelastic to complete superelastic,and the stress-train curve shape was stable.With increasing n,the superelastic residual strainε_r decreased and the superelastic strain recovery ratioη_s of Ti-50.8Ni alloy increased,while theε_r andη_s in Ti-50.8Ni-0.3Cr alloy kept at lower and higher values,respectively. The superelastic of Ti-50.8-0.3Cr alloy was stable.更多还原