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从合金热力学的角度,采用一种普适化的三亚晶格热力学模型,辅助以第一性原理总能计算的方法,研究了常用于添加在L10-TiAl基金属间化合物中的12种过渡族金属元素的占位行为随Ti/Al比和温度的变化情况。结果表明,在1173 K,合金化元素含量固定为2%(原子分数),Ti/Al比从0.6增加至1.4时,Ti和Al本身具有很强的占位有序性。当温度固定为1173 K,Ti/Al比从0.6增加至1.4时,合金化元素按其占位行为可以分为两大类,其中,V,Ta,Mo,Mn,Cr,Zn和W元素随Ti/Al比的增加,其占位行为在Ti/Al=1附近出现了从占Ti位到Al位的突变;Zr,Nb,Tc,Co和Ag元素的占位行为随Ti/Al比变化没有明显变化。当Ti/Al=1,合金体系固定为Ti0.49Al0.49M0.02,温度从200 K增加至2000 K时,合金化元素按其占位行为同样可以分为两大类,其中,V,Ta,Mo,Tc,Co,Mn,Cr,Zn和W元素随温度升高,其占位行为从完全无序转变为具有明显的占位倾向性;Zr,Nb和Ag元素的占位行为随温度升高没有显著变化。比较表明,Ti/Al比对合金化元素占位行为的影响大于温度的影响。该结果与大部分文献报道的实验和计算结果吻合。
From the perspective of alloy thermodynamics, a generalized Sanya lattice thermodynamic model is used to assist in the calculation of the total energy of the first-principles, the 12 transition families commonly used in the addition of L10-TiAl-based intermetallic compounds The occupancy behavior of metal elements varies with Ti / Al ratio and temperature. The results show that at 1173 K, the content of alloying elements is fixed at 2% (atomic fraction) and the Ti / Al ratio increases from 0.6 to 1.4, Ti and Al themselves have strong site-specific ordering. When the temperature is fixed at 1173 K and the Ti / Al ratio increases from 0.6 to 1.4, the alloying elements can be divided into two categories according to their occupying behavior. Among them, elements V, Ta, Mo, Mn, Cr, Zn and W The Ti / Al ratio increases with the increase of Ti / Al ratio. The change of the occupancy of Zr, Nb, Tc, Co and Ag elements changes with Ti / Al ratio No significant change. When Ti / Al = 1, the alloy system is fixed as Ti0.49Al0.49M0.02, when the temperature increases from 200 K to 2000 K, alloying elements can also be divided into two categories according to their occupying behavior. Among them, V, Ta , The contents of Mo, Tc, Co, Mn, Cr, Zn and W increased with temperature, and their placeholder behavior changed from completely disordered to obvious placeholder. The occupancy behavior of Zr, Nb and Ag elements varied with temperature No significant change in increase. The comparison shows that the effect of Ti / Al ratio on the occupancy of alloying elements is greater than that of temperature. This result is consistent with the experimental and calculated results reported in most of the literature.