Cr、Mn、Co、Ni掺杂对Al_(13)Fe_(4)相稳定性和力学性能影响的第一性原理研究

The effect of Cr,Mn,Co,and Ni on stability and mechanical properties of the AlFe phase from first-principles

采用基于密度泛函理论的第一性原理计算方法,系统地研究了不同掺杂浓度下过渡族元素Cr、Mn、Co、Ni在Al_(13)Fe_(4)相中的占位情况、结构稳定性和机械性能.计算得到所有的Al_(78)(Fe_(24)-xMx)(M=Cr、Mn、Co、Ni;x=1,2,4)相都具有良好的热力学稳定性和机械稳定性.相同掺杂浓度化合物的形成焓按如下顺序减小:Al_(78)(Fe_(24)-xCrx)>Al_(78)(Fe_(24)-xMnx)>Al_(13)Fe_(4)>Al_(78)(Fe_(24)-xNix)>Al_(78)(Fe_(24)-xCox).形成焓的降低增加了Al_(13)Fe_(4)相成核驱动力,Co和Ni有利于促进Al-Fe合金中Al_(13)Fe_(4)相形核,细化Al_(13)Fe_(4)相.过渡族元素可以改善金属间化合物的脆性,增强塑性变形能力.并且随着掺杂浓度的增加,过渡族元素的加入对脆性的改善呈先增大后减小的趋势.

Al_(13)Fe_(4) intermetallic compounds were systematically studied using first-principles methods based on the addition of 3 d transition elements M(M=Cr,Mn,Co,Ni)on different substitution sites with different doping concentrations.It is found that Al_(78)(Fe_(24)-xMx)compounds can be formed and their crystal structures are thermodynamically stabile.The formation enthalpy of compounds with the same concentration decreases according to the following order:Al_(78)(Fe_(24)-xCrx)>Al_(78)(Fe_(24)-xMnx)>Al_(13)Fe_(4)>Al_(78)(Fe_(24)-xNix)>Al_(78)(Fe_(24)-xCox).The reduction of formation enthalpy increases the nucleation driving force,suggesting that Co and Ni are the most suitable elements for stimulating the nucleation of the Al_(13)Fe_(4) phase in Al-Fe alloys.M elements can improve the brittleness of intermetallic compounds and enhance the plastic deformation ability.As the doping concentration increases,the brittleness improvement through the addition of M elements is found to firstly increase and subsequently to decrease.