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用分子动力学方法模拟了沿〈001〉晶向应变加载和卸载情况下单晶铁中体心立方(bcc)与六方密排(hcp)结构的相互转变,分析了相变的可逆性和微结构演化特征.微观应力的变化显示样品具有超弹性性质,而温度变化表明在相变和逆相变过程中均出现放热现象.相变起始于爆发式均匀形核,晶核由块状颗粒迅速生长为沿{011}晶面的片状分层结构;而卸载逆相变则从形核开始就呈现片状形态,且相界面晶面指数与加载相变完全一致,表现出形态记忆效应.在两hcp晶核生长的交界面易形成面心立方(fcc)堆垛层错.fcc通过在hcp晶粒内合并和晶粒间位置调整,最终形成贯穿hcp单晶的fcc结构.卸载过程由hcp至bcc转变相对缓慢,且fcc位置不再改变.最后,给出了上述相变可逆性的径向分布函数分析.
The interaction between body centered cubic (bcc) and hexagonal close-packed (hcp) structures in single-crystal iron under strain loading and unloading in the <001> direction was modeled by molecular dynamics method, and the reversibility and micro The evolution of microstructure shows that the sample has hyperelastic properties and the temperature change indicates that exothermic phenomena occur during both phase transformation and reverse phase transformation.Phange of phase begins with uniform nucleation and the nuclei consist of massive The particles grow rapidly into a sheet-like layered structure along the {011} crystal plane. However, the unloaded reverse phase changes from the nucleation to the lamellar morphology, and the interfacial interphase index and loading phase change are completely consistent, showing morphological memory Effect in the two hcp nucleation at the interface easy to form face-centered cubic (fcc) stacking fault .fcc hcp grain by the merger and the intergranular position adjustment, the final formation of fcc structure throughout the hcp single crystal unloading The process of hcp to bcc transformation is relatively slow, and the fcc position is no longer changed.Finally, the radial distribution function of the above phase transformation reversibility is given.