Solidification pathway and phase transformation behavior in a beta-solidified gamma-TiAl based alloy
来源期刊：JOURNAL OF MATERIALS SCIENCE TECHNOLOG2019年第11期
论文作者：H.Xu X.B.Li W.W.Xing L.Shu Y.C.Ma K.Liu
文章页码：2652 - 2657
摘 要：The phase transformation behavior of an as-cast Ti-42Al-5 Mn（at.%） alloy after subsequent quenching from 1380 ℃ to 1000 ℃ was investigated based on the differential thermal analysis（DTA）,electron probe micro analyzer-backscattered electrons（EPMA-BSE）,transmission electron microscope（TEM） and X-ray diffraction（XRD）.The results show that,the solidification path can be summarized as follows:Liquid→Liquid+β→β→β→α→β+α+γ→βo+α2+γ→βo+γ+α2/γ→βo+γ+α2/γ+βo,sec,with the phase transformation α→β temperature（Tβ）=1311℃,phase transformation γ→β temperature of(Tγsolv)=1231℃,phase transformation α2→α or βo→β temperature(Tα2→α/Tβo→β)=1168 C,eutectoid temperature(Teut)=1132 ℃ and Tα2/γ→βo,sec≈1 120℃.In comparison with Ti-42 Al alloy,the Teut and Tγsolvare slightly increased while both the Tp is decreased obviously by 5% Mn addition.When quenched from the temperature of 1380-1260 ℃,the martensitic transformation β→α’ could occur to form the needlelike martensite structure in β area.This kind of martensitic structure is much obvious with the increase of temperature from 1260℃ to 1380 ℃.When the temperature is below Tγsolv（1231℃）,the γ grains would nucleate directly from the β phase.For the temperature slightly lower than Teut（1132℃）,the dotted βo,sec phases could nucleate in the lamellar colonies besides the γ lamellae precipitated withinα2 phase.Finally,at room-temperature（RT）,the alloy exhibits（po+α2+γ） triple phase with microstructure of βo+lamellae+γ,of which the lamellar structure consists of α2,γ and βo,sec phases.The phase transformation mechanisms in this alloy,involving β→α’,β→γ,α2→α2/γ and α2→βo,sec were discussed.
H.Xu1,2，X.B.Li1，W.W.Xing1，L.Shu1，Y.C.Ma1，K.Liu1
1. Institute of Metal Research,Chinese Academy of Sciences
摘 要：The phase transformation behavior of an as-cast Ti-42Al-5 Mn（at.%） alloy after subsequent quenching from 1380 ℃ to 1000 ℃ was investigated based on the differential thermal analysis（DTA）,electron probe micro analyzer-backscattered electrons（EPMA-BSE）,transmission electron microscope（TEM） and X-ray diffraction（XRD）.The results show that,the solidification path can be summarized as follows:Liquid→Liquid+β→β→β→α→β+α+γ→βo+α2+γ→βo+γ+α2/γ→βo+γ+α2/γ+βo,sec,with the phase transformation α→β temperature（Tβ）=1311℃,phase transformation γ→β temperature of(Tγsolv)=1231℃,phase transformation α2→α or βo→β temperature(Tα2→α/Tβo→β)=1168 C,eutectoid temperature(Teut)=1132 ℃ and Tα2/γ→βo,sec≈1 120℃.In comparison with Ti-42 Al alloy,the Teut and Tγsolvare slightly increased while both the Tp is decreased obviously by 5% Mn addition.When quenched from the temperature of 1380-1260 ℃,the martensitic transformation β→α’ could occur to form the needlelike martensite structure in β area.This kind of martensitic structure is much obvious with the increase of temperature from 1260℃ to 1380 ℃.When the temperature is below Tγsolv（1231℃）,the γ grains would nucleate directly from the β phase.For the temperature slightly lower than Teut（1132℃）,the dotted βo,sec phases could nucleate in the lamellar colonies besides the γ lamellae precipitated withinα2 phase.Finally,at room-temperature（RT）,the alloy exhibits（po+α2+γ） triple phase with microstructure of βo+lamellae+γ,of which the lamellar structure consists of α2,γ and βo,sec phases.The phase transformation mechanisms in this alloy,involving β→α’,β→γ,α2→α2/γ and α2→βo,sec were discussed.
关键词：
