电磁搅拌对半固态AZ91D镁合金组织的影响

Microstructure of semi-solid AZ91D alloy solidified during electromagnetic stirring

研究了电磁搅拌参数对连续冷却条件下AZ91D镁合金组织的影响.结果表明:当电磁搅拌的频率达到或高于50Hz时,半固态AZ91D镁合金浆料或坯料组织中的球状初生固相越来越多,越来越圆整;在电磁搅拌频率为200Hz和冷却速率较低的条件下,搅拌的功率越大,半固态AZ91D镁合金组织中的球状初生固相越多,晶粒也越细小.在电磁搅拌条件下,AZ91D镁合金熔体的激烈流动导致较为均匀的温度场和溶质场、更加剧烈的温度起伏,促进了半固态AZ91D镁合金球状组织的形成.半固态重熔加热使半固态AZ91D镁合金坯料初生固相的形态发生进一步的球化.

Using a self-made rotationally electromagnetic stirring device and alloy melt quenching technology, the effect of electromagnetic stirring parameters on the microstructures of semi-solid AZ91D alloy was investigated. The results show that the spherical primary grains in the semi-solid AZ91D slurry or billet become more and rounder when the stirring frequency reach 50 Hz or above. When the stirring frequency is 200 Hz and the cooling rate is lower, the larger the stirring power, the more and the finer the spherical primary grains are. The theoretical analysis indicates that the strong flow motion leads to more even temperature field and solute field and stronger man-made temperature fluctuation in the AZ91D alloy melt so that the fine spherical primary grains are formed in the semi-solid AZ91D magnesium alloy slurry. When the billet of AZ91D magnesium alloy is reheated to the solidus and liquidus temperature region, the primary grains will be more spherical.