保温时间、冷却速率以及预变形对钴金属γ→ε相变行为的影响

Effects of holding time, cooling rate and predeformation on microstructural characteristics of cobalt undergoing γ→ε transformation

研究保温时间、冷却速度以及预变形对金属钴γ→ε相变行为的影响。重点使用电子背向散射衍射技术表征γ→ε转变的微观组织及织构演变行为。结果表明,经过γ→ε转变后金属钴的微观组织结构为双相组织(γ相和ε相):γ相中存在Σ3特殊晶界,ε相中存在70.5°/<1120>特殊晶界;且由于这些特殊晶界的存在,导致晶粒细化和基面织构弱化。保温时间和冷却速度对残余奥氏体(γ相),Σ3晶界以及70.5°/<1120>晶界含量的影响,不存在明显的规律。然而,随着预变形程度的增加,奥氏体含量、Σ3晶界和70.5°/<1120>晶界的含量都随之增加,且晶粒细化及织构弱化效应显著。对γ→ε相变后板条组织的表征,发现不同形态特征的板条组织可由块状和三角形为基本单元所构成。

The effect of holding time, cooling rate and predeformation on microstructural characteristics of a cobalt （Co） undergoing γ→ε transformation was investigated. The microstructural characteristics and texture evolution during γ→ε transformation were analysed by using electron backscatter diffraction equipped in field emission gun scanning electron microscope. The results show that a dual-phase microstructure （γ phase and ε phase）. Σ3 boundaries exist in γ phase and special boundaries with misorientation （70.5°/〈11^-22〉） are observed ε phase. Refining grain size and weakening basal texture are via Σ3 boundaries and 70.5°/〈11^-22〉 boundaries. There are no obvious regularity for the effects of holding time and cooling rate on the amounts of the retained austenite, 70.5°/〈11^-22〉boundaries and Σ3 boundaries. However, the predeformation extent markedly affects the amounts of the retained austenite, 70.5°/〈11^-22〉 boundaries, Σ3 boundaries, grain refinement and texture weaken. The morphology characteristics of plate-like products are consisted of the blocky units and the triangle units.