二次重熔工艺对ZA92镁合金半固态浆料固相颗粒的影响

Influence of Secondary Remelting Process on Semi-Solid Microstructure of ZA92 Magnesium Alloy

采用自孕育法制备ZA92镁合金半固态坯料，研究了二次重熔温度和时间对ZA92镁合金半固态固相颗粒的影响。结果表明：二次重熔温度升高和重熔时间的延长，合金的固相率减小，平均晶粒尺寸和平均圆整度呈现先减小后增大的变化趋势。当在570～580℃保温30min或在590℃保温20min时，可获得理想的半固态浆料固相颗粒，其平均晶粒尺寸、圆整度和固相率分别在83~86μm、1．37～1．59和62．3％~67．8％。晶粒前期以根部熔断和亚晶界分离机制进行分离，后期晶粒的球化、粗化满足LSW理论。

The semi-slid billets of ZA92 magnesium alloy were prepared by self-inoculation method（SIM）. The influence of secondary remelting temperature and time on semi-solid solid particle was studied. Results show that with increasing secondary remelting temperature and prolonging remelting time, solid fraction of ZA92 magnesium was decreased, and the average grain size and the average roundness decreased firstly, and then increased. When holding at 570-580 ℃ for 30 min or 590℃ for 20 min, the idea solid particle was obtained. The average grain size, average roundness, and solid fraction respectively are 83-86 μm, 1.37-1.59 and 62.3%-67. 8% respectively. At early stage, the grain separation was realized by root remelting mechanism and subboundary senaration mechanism. At later stage, grain spheroidization and coarsening meet LSW theory.