Abstract Fe-Mn-based alloys show the shape memory effect which is mainly related to the FCC-HCP martensitic transformation. Cr is one of the additional elements which improve the properties of these alloys. In the present work structural data are obtained for the FCC austenite, and both martensitic structures, HCP and BCC, for an extended composition range where the FCC-HCP transition takes place. Lattice parameters are determined by X-Ray diffraction measurements performed at room temperature. The volume change between the austenite and each martensitic structure plays a significant role on relevant properties for martensitic transformations, like the strain energy associated to the transition. The effect of Mn and Cr on lattice parameters and volume change between FCC and HCP is determined and modeling of the data is presented. This result allows estimating the strain energy associated to the phase change. By using this information, the strain energy contribution to the balance of energy for the HCP nucleation is discussed. The addition of Cr decreases the volume change between FCC and HCP for contents larger than 12 wt% Cr which leads to a decrease of the strain energy. Both effects favor an increased shape memory effect associated to the FCC-HCP martensitic transition.

中文翻译：

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Mn和Cr对Fe-Mn-Cr形状记忆合金FCC-HCP马氏体相变过程中结构参数和应变能的作用

摘要 Fe-Mn基合金表现出形状记忆效应，主要与FCC-HCP马氏体相变有关。Cr是改善这些合金性能的附加元素之一。在目前的工作中，获得了 FCC 奥氏体和马氏体结构 HCP 和 BCC 的结构数据，用于发生 FCC-HCP 转变的扩展成分范围。晶格参数由在室温下进行的 X 射线衍射测量确定。奥氏体和每个马氏体结构之间的体积变化对马氏体转变的相关特性起着重要作用，例如与转变相关的应变能。确定了 Mn 和 Cr 对 FCC 和 HCP 之间的晶格参数和体积变化的影响，并提供了数据建模。该结果允许估计与相变相关的应变能。通过使用这些信息，讨论了应变能对 HCP 成核能量平衡的贡献。对于大于 12 wt% Cr 的含量，Cr 的添加降低了 FCC 和 HCP 之间的体积变化，从而导致应变能降低。这两种效应都有利于与 FCC-HCP 马氏体转变相关的形状记忆效应的增加。