保温时间对A356铝合金半固态组织熟化的影响

Effect of Holding Time on Semi-solid Microstructure of the A356 Alloy Fabricated by Rotating-rod Induced Nucleation Method

采用转棒诱导形核法制备A356铝合金半固态浆料,研究保温时间对半固态浆料组织的影响。结果表明,随着保温时间延长,初生α-Al相等效直径不断增大,但初生α-Al的形状因子先降低后升高,符合Oswald长大机制。在保温1min时初生α-Al相的等效直径最小,约为54μm,形状因子为0.89,单位面积内的颗粒数最多约为175/mm^2;在保温5min时,初生α-Al相形状因子最小,为0.83,其等效直径约为74μm,单位面积内的颗粒数约为130/mm^2;保温20min时,初生α-Al的形状因子最大,为0.97,单位面积内的颗粒数约为70/mm^2。

The rotating-rod induced nucleation（RRIN）was adopted to fabricate the semi-solid slurry of A356 alloy,and influence of holding time on the microstructure of A356 aluminum alloy semi-solid slurry was investigated.The results show that,with the increase of holding time,the primary phase size is increased gradually,however,the shape factor of the primaryα-Al is decreased firstly and then increased,which follows the Oswald ripening mechanism.With holding for 1min,the equivalent diameter of the primary phase is about 54μm with shape factor of 0.89,while the number of particles per unit area is about 175/mm2.With the holding time of 5min,the primaryα-Al shape factor is 0.83,and its equivalent diameter reaches about 74μm,and number of particles per unit area is about 130/mm2.However,the shape factor reaches the largest with the holding time of 20 min,as much as 0.97,and the number of particles per unit area is about 70/mm2.