(北京航空材料研究院,北京 100095)
摘 要: 在Ti-(44～48)Al-(3～6)Cr(摩尔分数, %) 的三元合金中，存在B2结构的体心立方有序β2 相，其形成与含Cr量有关。β2相铸态成分可表示为：Ti55Al33Cr12。β2相是该合金中显微硬度最高的相，其硬度值随合金中Cr 含量增加而提高。β2相常分布于γ 晶界，起阻碍晶粒长大作用。
关键字: TiAl基合金 β2相 Cr的作用
（Institute of Aeronautical Materials, Beijing 100095, P. R. China）
Abstract:In the ternary alloys of Ti-(44~48)Al-(3~6)Cr(mole fraction, %), there is an ordered bccβ2 phase with B2 structure. The formation of this phase is related to the content of Cr. 0.5%(volume fraction) β2 phase can be precipitated in as-cast Ti-44Al-3Cr alloy. The amount of β2 phase reaches 6%(volume fraction) after long time soaking from 900 ℃ to 1200 ℃. However, β2 phase disappears when holding long time above 1250℃. The composition of β2 phase can be expressed as Ti55Al33Cr12. The microhardness of β2 phase is the highest among all the phases of the alloy and its microhardness increases with the increase of Cr content in alloys. β2 phase often distributes at the grain boundaries of γ phase and retards the growth of γ phase grains. The deformation capability of β2 phase is the weakest in the phases of the alloy and it inhibits the long distance slip, therefore, β2 phase would make slip dispersive and delay the initiation of cracks.
Key words: TiAl base alloys β2 phase effect of Cr
