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相(ω_a)。低于500℃时效,发生β→B+ω_(iso)→β+α转变。在400℃以下,α相均匀长大,450—500℃时效,初期由等温ω相(ω_(iso))转变的α相不再是均匀长大,在原始β相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,在多数α相的片中有内挛晶。内孪晶的量随着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相片的边缘产生台阶和错动。低温或商温转变的α相,其与β相的晶体学取向都符合Burgers关系。本工作仅在一只试样的选区衍射花样中有弧形衍射斑,这最可能是TiH_2析出的结果。
The phase transformation of Ti-4Al-7Mo-10V-2Fe-1Zr metastable β-Ti alloy has been studied by TEM. The results showed that the athermal ω-phase exists as quenched; the phase transformations undergo in aging at various temperatures as: below 500℃, β→β+ω (isothermal)→β+α; below 400℃, α-phase growing uniformly; between 400-500℃, no more α-phase altered from isothermal ω-phase first uniformly growing, yet selectively growing along the prior β-phase boundaries and at the local crystal defect sites;and beyond 550℃, direct reaction β→β+α and inner twinns forming in the most α plates which decrease in amount with the prolonged aging, then vanish finally. The ledges and displacement at the edge of the α plates were found to follow the above-mentioned process. It was indicated that the orientation relationship between β and α seems to obeythe Burgers' relationship no matter how the aging condition. Only one specimen was revealed the arced spots in the selected area electron diffraction pattern which may be caused by the precipitation of TiH_2.
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