The properties of nonequilibrium face-centered-cubic (fcc) and body-centered-cubic (bcc) Fe–Cu alloys were studied using the first-principles full-potential linearized augmented plane wave method within the generalized gradient approximation. The ab initio calculation results are compared quantitatively with the magnetic moment and atomic volume observed for mechanically alloyed FexCu100–x (x = 0 to 100) supersaturated bcc and fcc solid solutions. The calculations show that Cu alloying leads to a small enhancement of the magnetic moment of bcc Fe. The fcc Fe moment, on the other hand, experiences a more pronounced increase into a high-spin state upon alloying with Cu. It reaches approximately the same value as that in the bcc alloys for all Cu concentrations where fcc solutions are obtained in experiments, corroborating previous ab initio calculations using different methods. The magnetic moment increases are accompanied by an atomic volume expansion. Both the calculated moment and volume behavior are in good agreement with those measured for fcc and bcc Fe–Cu solutions. The magnetovolume expansion upon magnetic interaction between the alloyed Fe and Cu, rather than the positive heat of mixing, constitutes the primary reason for the atomic volume increase observed.
采用广义梯度近似的第一原理全电势线性化增强平面波法研究了非平衡面心立方(fcc)和体心立方(bcc)铁铜合金的性质。将 ab initio 计算结果与机械合金化的 FexCu100-x(x = 0 至 100)过饱和 bcc 和 fcc 固溶体的磁矩和原子体积进行了定量比较。计算结果表明,铜合金化导致 bcc 铁的磁矩略有增强。另一方面,与铜合金化后,fcc 铁的磁矩会更明显地增加到高自旋态。在实验中获得 fcc 溶液的所有铜浓度下,fcc 铁的磁矩都达到了与 bcc 合金大致相同的值,这与之前使用不同方法进行的 ab initio 计算结果相吻合。磁矩的增加伴随着原子体积的膨胀。计算得出的磁矩和体积行为与 fcc 和 bcc 铁-铜溶液的测量结果十分吻合。合金铁和铜之间的磁相互作用导致的磁体积膨胀,而不是正混合热,是观察到的原子体积增加的主要原因。