【摘要】 研究了NiTi(Fe)合金在不同温度下的伪弹性行为,并在加应力的条件下作了相应的x光衍射和电子衍射研究,获得如下结果:(1)在N-I相变点T_I以上,应力应变曲线已出现回线面积较小的超弹型回线,这是由于应力感生无公度相引起的.(2)在R_s≤T<T_i范围,当温度趋近于开始形成R相的温度R_s(≈-80℃)时,应力应变曲线由超弹型转变为铁弹型回线,且屈服应力不断降低,残余应变不断增加,这是由于在R_s附近模量最软所致. 室温下,接近等原子比的NiTi合金存在R相(R_s≈40℃).应力应变曲线偏离线性关系的初始阶段,实时x光衍射分析表明合金内发生了应力感生R相畴的再取向.继续增加应力,出现应力感生的马氏体相的衍射线.更多还原

【Abstract】 The pseudo-elasticity of NiTi(Fe) alloy has been studied at diffe-rent temperatures and the stressed in situ X-ray and electron diffraction analysishave been performed at room temperature. The following results were obtained: (1)Above incommensurate transition temperature T_i, the stress-strain curve appears assuperelastic loop of small loop area, due to the stress induced incommensurate phaseas confirmed by in situ electron microscope experiment. (2) When R_s≤T<T_i, thestress-strain curve turns into ferroelastic type from superelastic type, and the yieldstress decreases while residual strain increases because of the elastic softening nearR_s. R phase is present in NiTi alloy at room temperature (R_s is about 40℃). Insitu X-ray diffraction has shown that stress induced reorientation of R domains takesplace at the early stage of deviation from linearity on stress-strain curve. Furtherincreasing the stress results in a yielding terrace of stress-strain curve associatedwith the appearance of diffraction patterns of stress induced martensite.更多还原