冷轧对TiNi合金组织及力学性能的影响

Influence on Microstructure and Mechanical Properties of TiNi Alloy producing by Cold rolling

摘要:

在室温下对TiNi合金进行轧制，采用OM、XRD、DSC、TEM等分析检测技术，研究了冷轧变形量对TiNi合金显微组织演变、力学性能的影响规律，探讨了合金变形的微观机制。结果表明：TiNi合金在冷轧变形过程中，组织发生了B2奥氏体相向B19’马氏体相的转变；随变形量的增加，组织的不均匀变形增加，出现了纳米晶和非晶相。冷轧后的TiNi合金在拉伸过程中仅表现出奥氏体相、马氏体相的弹性变形和塑性变形阶段，应力诱发马氏体相变阶段消失，表现为连续屈服过程。TiNi合金在不同的应变阶段具有不同的变形机制：当应变量为0<ε≤0.3时，合金的主要变形机制为位错滑移；当应变量ε>0.3时，合金以孪生和位错滑移相结合的变形机制进行变形。

Abstract:

The effect of rolling at room temperature on the microstructure evolution and mechanical properties of TiNi alloy was investigated by optical microscopy (OM), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and transmission electron microcopy (TEM) technique. The results indicate that the B2 austenite phase to B19" martensite phase transformation has occurred in the TiNi alloy; when the deformation is intensified, the non-uniform deformation of microstructure increases, and nanocrystalline and amorphous phases appear. Cold-rolling TiNi alloy exhibits only the elastic deformation and plastic deformation stages of the austenite and martensite phases during the stretching process, and the stress-induced martensite phase-transformation disappears, showing a continuous yielding process. The TiNi alloy have different deformation mechanism at different deformation mechanism: when the strain is 0<ε≤0.3, the main deformation mechanism of the alloy is dislocation slip; When the strain ε>0.3, the deformation mechanism is the combination of twinning and dislocation slip.