静态退火对Mg-Gd-Y-Zr挤压合金的微结构与织构影响

Effect of static annealing on microstructure and texture of Mg-Gd-Y-Zr extruded alloy

摘要:

本文研究了Mg-9Gd-4Y-0.6Zr挤压合金在静态退火过程中的微结构与织构的演变。采用金相显微术、扫描电子显微术、透射电子电子显微术、差热分析仪、XRD织构测试仪及EBSD分析技术表征了合金的晶粒长大、析出相沉淀及织构改变。结果表明，退火初期的晶粒尺寸下降是由再结晶引起的；晶间不均匀变形诱发了晶间的局部析出，继而抑制了再结晶过程。织构分析表明，热挤压产生了常见的基面纤维织构和不常见的柱面纤维织构，即c轴平行于挤压方向；在静态再结晶过程中，新晶粒形核会弱化柱面纤维，而晶粒长大过程会强化柱面纤维。晶界与亚晶界上的大量析出相抑制了织构改变。

Abstract:

The evolution of microstructure and texture for the Mg-9Gd-4Y-0.6Zr extruded alloy during static annealing was investigated. The grain growth, precipitation and texture modification were characterized by optical microscopy, scanning electron microscopy, transmission electron microscopy, differential scanning calorimeter, XRD texture instrument and EBSD. The results show that the recrystallization process resulted in the grain refinement at the initial stage of static annealing, and that the intergranular deformation stimulated local precipitating which in turn inhibited the recrystallization process. The texture analysis indicates that the hot extrusion produces the conventional basal fiber with {0001} // ED and the unusual prismatic fiber with c axis // ED. During static recrystallization, the process of grain nucleation weakens the prismatic fiber, while the process of grain growth strengthens it. A large number of plate phases precipitate at grain boundaries along with subgrain boundaries, which significantly inhibits the texture modification.