摘要
Microstructural evolution and dynamic recrystallization(DRX)mechanisms of a Ti-48Al-2Cr-2Nb(at.%)alloy prepared by selective electron beam melting(SEBM)during hot deformation at 1150℃and 0.1 s^(-1)were investigated by hot compression tests,optical microscope(OM),scanning electron microscope(SEM),electron back-scattered diffraction(EBSD)and transmission electron microscope(TEM).The results show that the initial microstructure of the as-SEBMed alloy exhibits layers of coarseγgrains and fineγ+α_(2)+(α_(2)/γ)lamellar mixture grains alternately along the building direction.During the early stage of hot deformation,deformation twins tend to form within the coarse grains,facilitating subsequent deformation,and a small number of DRX grains appear in the fine-grained regions.With the increase of strain,extensive DRX grains are formed through different DRX mechanisms in both coarse and fine-grained regions,involving discontinuous dynamic recrystallization mechanism(DDRX)in the fine-grained regions and a coexistence of DDRX and continuous dynamic recrystallization(CDRX)in the coarsegrained regions.
采用热压缩实验、光学显微镜(OM)、扫描电镜(SEM)、电子背散射衍射(EBSD)和透射电镜(TEM)研究了电子束选区熔化(SEBM)制备的Ti-48Al-2Cr-2Nb合金(摩尔分数,%)在1150℃和0.1 s^(-1)条件下热变形过程中的显微组织演变和动态再结晶(DRX)机制。结果表明:合金的初始显微组织为沿打印方向交替分布的γ粗晶层和γ+α_(2)+(α_(2)/γ)细晶层。热变形初期,粗晶中形成有利于后续变形的变形孪晶,细晶区域发生少量动态再结晶(DRX)。随着应变的增加,粗晶区和细晶区通过不同的再结晶机制形成大量的DRX晶粒。其中,细晶区的DRX机制为不连续动态再结晶(DDRX),粗晶区的DRX机制包括DDRX和连续动态再结晶(CDRX)。
基金
the financial supports from the Shaanxi Province Key Research and Development Projects,China(No.2023KXJ-071)
the National Natural Science Foundation of China(Nos.52274402,52174381)。
