【摘要】 为分析Fe-Mn-Si记忆合金的疲劳特性,采用与该材料具有相同母相的304不锈钢作为对比材料,通过弯曲疲劳试验法测量两者在应变幅值为±3.5%时的疲劳断裂次数,并利用X射线衍射法(XRD)和场发射扫描电镜(SEM)分析试样相组成和断口形貌。结果表明:Fe-Mn-Si记忆合金和304不锈钢的弯曲疲劳断裂次数分别为1159次和63次,断口形貌依次为韧窝和撕裂棱。前者断裂时的物相基本为ε马氏体,而后者几乎全部由α′马氏体组成,表明应力诱发Fe-Mn-Si记忆合金发生γ→ε马氏体相变。相变过程中,应力集中程度和裂纹扩展速度降低是Fe-Mn-Si记忆合金疲劳强度提高的机理。更多还原

【Abstract】 In order to analyze the fatigue properties of Fe-Mn-Si memory alloy,the 304 stainless steel that had the same parent phase was chosen as contrast material.The fatigue cycles were measured by bending fatigue test under the ±3.5% strain amplitudes,and the phase compositions and fractures appearances of specimens were observed with X-ray diffraction(XRD) and field emission scanning electron microscope(SEM).The experimental results show that the bending fatigue break cycles of Fe-Mn-Si memory alloy and 304 stain steel is 1159 and 63,respectively,their fracture appearances are dimples and tearing ridges in turn.When the specimens break,the former phase compositions are almost ε-martensite,while the latter were basically composed by α′-martensite.The phenomenon indicates that the bending stress induces the γ→ε martensite phase transformation of Fe-Mn-Si memory alloy,and the mechanism of fatigue strength improvement inside Fe-Mn-Si memory alloy is that stress concentration and crack speed reduce in the phase transition process.更多还原