【摘要】 在超弹性NiTi 合金室温加载、卸载的应力循环过程中,在同一样试上同时测量了应变、模量、电阻率以及内耗随应力的变化,研究了应力循环周数对上述四个参数的影响.结果表明:在增加应力至应变为4%后卸载时,试样表现了完整的超弹性,即应力卸载至零时,应变完全回复到零,这说明全部应变都是由应力诱导的可逆相变提供的.在增加应力时,电阻率单调上升并变平,模量出现极小值而内耗出现极大值;减小应力时,上述过程滞后地出现.当试验温度远高于母相转变为无公度I 相的温度T_I 时,以及试验温度低于M_f 点时,上述超弹性以及变载过程中出现的电阻、内耗及模量的变化特征均消失.将上述结果和NiTi含金在变温过程中电阻、内耗及模量的变化规律进行对比,以及对应力诱导循循环前后试样的X 光衍射分析结果均表明,上述超弹性是由于NiTi 合金中应力诱导的无公度相I/公度相C间的可逆转变所提供的.由于应力诱导I/C 转变的可逆性,因此这一转变将对NiTi 合金的双程形状记忆效应产生一定的影响.研究了应力循环周数对可逆I/C 转变的影响.更多还原

【Abstract】 The interal friction Q-1,modulus f²,resistance R and the strain （?） of superelast-icity Ni51Ti49 alloy in the process of stress-induced incommensurate/commensu-rate（I/C）transition was measured as a function of stress σ at room temperatu-re.This NiTi samples posses superelasticity up to about 4% of strain which isprovided completely with strain of stress-induced reversible I/C transition strainand this strain reverses zero when the stress is unloading to zero.A minimum in the f²-σ curves and a peak in the Q^-1-σ curves were observedfor the first time during the loading process and a reversible change appeareshysteretily in the unloading process.The compareson of these phenomenons withathermal transition of I/C in NiTi and the results of X-ray diffraction of stre-ss-cycled TiNi samples show that the superelasticity of NiTi alloy is provided com-pletely with strain of stress-induced reversible I/C transition.The mobility ofI/C phase interface was discussed.更多还原