摘要
Taking Ta–W alloy system as an example, the concentration formulae of alloy genes of DO3-type alloys in BCC structures were derived on the basis of the theory of alloy genes and the number of coordination atoms. The concentrations of alloy genes of DO3-TaW3 and DO3-Ta3W ordered alloys were calculated as functions of composition xW and ordering degree （s）. When s=smax, the concentrations of alloy genes of stoichiometric DO3-TaW3 compound are equal to those of alloys, that is, x8^Ta=0.25（at）,x4^W=0.5（at）,x8^W=0.25（at）The concentrations of alloy genes of stoichiometric DO3-Ta3W compound are also equal to those of alloys, that is,x0^Ta=0.25（at）,x4^Ta=0.5（at）,x0^W=0.25（at）. As ordering degree decreases, alloy genes of DO3-TaW3 and DO3-Ta3W ordered alloys will split. And the degree of splitting of alloy genes increases with the ordering degree decreasing. The atomic states and properties of DO3-TaW3 and DO3-Ta3W ordered alloys were calculated as a function of composition xW. The reason was pointed out that preparation of DO3-TaW3 and DO3-Ta3W intermetallic compounds is difficult due to small differences in their cohesive energies. It will provide theoretical guidance for the scientific designation to new candidate for ultra- high-temperature materials in areo-engine applications.
本文以Ta–W合金系为例,根据合金基因理论和配位原子数,推导出了BCC结构中DO3-型合金基因浓度的公式。计算了DO_3-TaW_3和DO3-Ta3W有序合金的基因浓度随成分xW和有序度(s)的变化。当s=smax时,化学计量比的DO_3-TaW_3化合物的合金基因浓度等于合金的浓度,即χ_8^(Ta)=0.25,χ_4~W=0.5,χ_8~W=0.25。化学计量比的DO_3-Ta_3W化合物的合金基因浓度也等于合金的浓度,即χ_0^(Ta)=0.25,χ_4^(Ta)=0.5,χ_0~W=0.25随着有序度的降低,DO_3-TaW_3和DO3-Ta3W有序合金将会发生分裂,且随着有序度的降低,合金基因分裂程度增加。计算了DO_3-TaW_3和DO_3-Ta_3W有序合金的原子状态和性质随成分xW的变化,指出了DO_3-TaW_3和DO_3-Ta_3W金属间化合物的制备非常困难的原因主要是由于它们的结合能差异小,为新一代超高温材料在航空发动机上的应用设计提供科学理论指导。
基金
Project(50954006) supported by the National Natural Science Foundation of China
Project(2014-12) supported by the Environmental Protection Department of Hunan,China
Project(2016TP1007) supported by the Hunan Provincial Science and Technology Plan Project,China
Project(2016-01) supported by the Development and Reform Commission of Hunan Province,China
