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用透射电镜研究了Ti-4Al-7Mo-10V-2Fe-1Zr亚稳β-Ti合金中的相变规律。结果表明,淬火态存在无热ω_a。低于500℃时效,发生β→β+ω_(iso)→β+α转变。在400℃以下α均匀长大,450～500℃时效,初期由亚稳ω_(iso)转变的α质点不再均匀长大,在原始β晶界和晶内局部处发生选择性长大。高于550℃时效,发生β→β+α直接转变、在α片内多数有内孪晶。内孪晶的数目随时效时间延长或温度升高而减少,最终消失。伴随这一过程在α片边缘产生台阶和错动。低温或高温转变的α,其与β的晶体学取向都附合Burgers关系。本工作仅在一只试样的选区衍射花样中出现弧形衍射斑,这可能是TiH_2析出的结果。
The phase transition of Ti-4Al-7Mo-10V-2Fe-1Zr metastable β-Ti alloy was studied by transmission electron microscope. The results show that there is no heat ω_a quenching state. Below 500 ℃ aging, β → β + ω iso (iso) → β + α transformation occurs. Α grows homogenously under 400 ℃ and aged at 450 ~ 500 ℃. The α mass transformed from the metastable ω iso (iso) at the initial stage no longer grows uniformly and grows selectively in the original β grain boundaries and in the local grains. Higher than 550 ℃ aging, the occurrence of β → β + α direct transformation, most of the α film within twins. The number of twins diminishes as the aging time increases or the temperature increases, eventually disappearing. Accompanying this process produces steps and misalignment at the edge of the alpha sheet. Low temperature or high temperature transformation of α, β and its crystallographic orientation are Burgers relationship. This work only appears in a sample of constitutive diffraction patterns arcuate diffraction spots, which may be TiH2 precipitation results.