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一、引言高温合金中拓扑密堆相是众所周知的σ,Laves,μ,δ,P相等的总称。这些相由于使不锈耐热钢及高温合金变脆而引起人们的重视。高温合金的合金化程度高且较为复杂,成分控制或热处理不当都会导致拓扑密堆相析出,从而恶化材料的热强性及韧性。因此,在拓扑密堆相的形成条件(包括成分及加工热处理条件)、析出的动力学等方面都已经进行了大量的研究。拓扑密堆相的晶体结构研究则是这些工作的基础。早在1927年,Bain和Griffith就发现某些Fe-Cr合金变脆原因是由于有成份为FeCr的
I. INTRODUCTION The topological dense phase in superalloy is the well-known common name of σ, Laves, μ, δ, P. Due to these phases so that the heat-resistant stainless steel and high temperature alloys become brittle and cause people’s attention. Superalloys have a high degree of alloying and are more complicated. Incorrect compositional control or heat treatment leads to precipitation of topologically dense phase, which deteriorates the thermal strength and toughness of the material. Therefore, a great deal of research has been conducted on the formation conditions of the topological dense phase (including the composition and processing heat treatment conditions) and the kinetics of precipitation. Topology The study of the crystal structure of dense phase is the basis of these efforts. As early as 1927, Bain and Griffith found that some Fe-Cr alloys became brittle due to the composition of FeCr