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利用电子背散射(EBSD)技术研究了近β型Ti-1300合金中次生α相的晶体学取向、几何生长方向、数量和分布与β相晶界特性之间的关系,以获悉次生α相的形核及其变体选择的本质。近β型Ti-1300合金经910℃固溶2 h+水淬处理,合金中出现一定比例的<110>_(_(70.5°))特殊晶界。该合金在910℃随炉缓慢冷却时,由β→α相变而来的次生α相与β相晶界的特性有明显关系。普通β/β晶界处生成的晶界α相自身取向不唯一,对自晶界α相变体形核作用不大,其两侧自晶界α相数量偏少;大角度特殊晶界<110>_(70.5°)两侧β晶粒存在共同的(110)面,这种取向有利于晶界α相为自晶界α变体提供异质形核,引发α变体在晶界两侧选择性生长;小角度特殊晶界<110>10.5°也会引发α变体选择性生长,但和大角度晶界不同,其选择性生长也可能只发生在晶界的一侧。
The relationship between the crystallographic orientation, geometric growth direction, number and distribution of secondary α phase in the β-type Ti-1300 alloy and the grain boundary properties of β phase was studied by using electron backscatter (EBSD) Phase Nucleation and the Nature of Variant Selection. Near-β Ti-1300 alloy was solution-treated at 910 ℃ for 2 h and water-quenched. A certain proportion of <110> _ (70.5 °) special grain boundaries appeared in the alloy. When the alloy is slowly cooled in the furnace at 910 ℃, the properties of the secondary α phase transformed from β → α and the grain boundary of β phase are obviously related. The grain boundary α phase formed at the ordinary β / β grain boundaries is not uniquely oriented. It has little effect on the nucleation of α phase transition from the grain boundaries, and the number of α phases from the grain boundaries on both sides is less. The large angle special grain boundaries <110 > (70.5 °), there exists a common (110) plane of β grains on both sides. This orientation favors the grain boundary α phase to provide heterogenous nuclei from the grain boundary α variants, and the α variants are induced on both sides of the grain boundaries Selective growth; small angle of special grain boundaries <110> 10.5 ° will also lead to α variant selective growth, but different from the large-angle grain boundaries, the selective growth may also occur only in one side of the grain boundary.