Local Lattice Strain around Alloying Element and Martensitic Transforamtion in Titanium Alloys
Local Lattice Strain around Alloying Element and Martensitic Transforamtion in Titanium Alloys
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钛合金合金元素周围的局部晶格应变与马氏体相变
DOI：
10.1051/matecconf/202032111009
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发表时间：
2020
影响因子：
--
通讯作者：
M. Yoshino
中科院分区：
文献类型：
--
作者：
M. Morinaga;H. Yukawa;M. Yoshino
由于合金中溶质原子和溶剂原子之间的尺寸失配，在溶质原子周围的晶格中引入了局部应变。本文首次用平面波赝势方法计算了钛合金的局域晶格应变。作为极端情况，还计算了各种bcc、fcc和hcp金属中空位周围的局域晶格应变。结果表明，体心立方钛和体心立方Fe的局部应变能都很高，发生了马氏体相变。由一系列计算表明，局域晶格中存储的应变能的大小与热能KBT相当，其中kB是玻耳兹曼常数，T是绝对温度。因此，合金中局部晶格应变的存在会影响相稳定性，这种稳定性随温度的变化而变化很大。例如，在二元钛合金中，局部晶格应变与马氏体相变开始温度ms相关。
Local strain is introduced into the lattice around solute atom due to the size mismatch between solute and solvent atoms in alloy. In this study, local lattice strains are calculated for the first time in titanium alloys, using the plane-wave pseudopotential method. As an extreme case, the local lattice strain around a vacancy is also calculated in various bcc, fcc and hcp metals. It is found that the local strain energy is very high in both bcc Ti and bcc Fe, where the martensitic transformation takes place. From a series of calculations, it is shown that the magnitude of the strain energy stored in the local lattice is comparable to the thermal energy,kBT, wherekBis the Boltzmann constant andTis the absolute temperature. Therefore, the presence of local lattice strains in alloy could influence the phase stability that varies largely depending on temperatures. For example, the local lattice strain correlates with the martensitic transformation start temperature,Ms, in binary titanium alloys.