Ti-1300合金中β/β晶界区β?α相变晶体学特征的EBSD分析

Crystallographic characteristics of β→α phase transformationat β grain boundaries in Ti-1300 alloy

摘要:

利用电子背散射电子技术(EBSD)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。经910℃固溶2h 水淬处理，合金中出现一定比例的<110>70.5?特殊晶界。合金自910℃随炉缓慢冷却，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?晶粒存在共同的(110)面，取向上有利于晶界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。

Abstract:

In order to obtain the essence of the nucleation phase and its variants selected of secondary α. Electronic backscatter diffraction (EBSD) has been employed to study the relationship between the crystal orientation, geometric growth direction, quantity, distribution of secondary α-phase and β-phase grain boundaries properties on nearly β-type Ti-1300 alloy. The alloy was equilibrated for 2 h at 910℃ and handled by water quenching. The alloy occurs a certain percentage of <110> 70.5° special boundaries. The alloy was slowly cooled in the furnace since 910℃, it has a significant relationship between the secondary α phase which from β→α phase transformation and β-phase grain boundaries properties. Common β/β grain boundary generated orientation is not unique, which has little effect on the nuclear of the Self -α phase grain boundary α phase variations, its relatively small number of both sides of since grain boundary α phase. The α phase grain boundary was generated by the common β/β grain boundary, its orientation was not unique. The common β/β grain boundary has little effect on the nuclear of the Self-α phase grain boundary α phase variations, and there are small number Self-α phase grain boundary both sides the α phase grain boundary. Both sides of the β grain which boundary is special high angle grain boundaries (<110>70.5°) have the same (110) plane. The orientation of the α phase grain boundary is favor for the formation of the heterogeneous nucleation of the Self-α phase grain boundary, which causes selective growth of the α variant on both sides in grain boundary; Special small-angle grain boundaries (<110>10.5°) also can cause α variant’s selective growth, but it is different from high-angle grain boundaries, the selective growth may only occur on one side of the grain boundary.