论文标题
替代合金中的低温有序，并注入非平衡空缺：fept案例
Low-temperature ordering in a substitutional alloy with injecting nonequilibrium vacancies: The FePt case
论文作者
论文摘要
在两个或多个物种的替代合金中实现成分有序状态通常对于改善其功能特性至关重要。为了产生高度有序的合金，由于空缺浓度不足（C_V）及其迁移率，通常需要对合金的长期高温（最高t = 1000 K）处理。但是，这种处理会影响形态并使功能合金的技术复杂化。从理论上讲，我们表明实际上重要的FEPT系统中的订购（Fe_xpt_1-X的X接近0.5）在合理的时间T = 450 K可以在t = 450 K时达到t <10^3 s，这是由于冷冻的非平衡空位。我们的模拟基于二烯方程，用于放松远程顺序参数，并考虑到合金中的订购动力学是由空位介导的。重要的是，此类模拟的结果与先前有关订购动力学的实验数据非常吻合。我们还发现，可以使用纳秒激光脉冲来实现足够的C_V = 10^-5，以实现有效的低温顺序。
Achieving the compositionally ordered state in a substitutional alloy of two or more species can often be even critical for improving its functional properties. To produce a highly ordered alloy, a longtime high-temperature (up to T=1000 K) treatment of the alloy is typically necessary because of insufficient vacancy concentration (c_v) and their mobility. However, such processing affects the morphology and complicates the technology of functional alloys. We show theoretically that the ordering in the practically important FePt system (Fe_xPt_1-x with x being close to 0.5) is already achievable at T=450 K for reasonable times t<10^3 s due to frozen nonequilibrium vacancies. Our simulation is based on the Dienes equation for relaxation of the long-range order parameter (S), with taking additionally into account that the ordering kinetics in the alloy is mediated by vacancies. Importantly, the results of such simulation are in good agreement with previous experimental data on the ordering kinetics. We also find that nanosecond laser pulses can be employed to achieve a sufficient level of c_v=10^-5 for effective low-temperature ordering.
