Abstract: The Microstructure of AlSi7Mg semi-solid alloy remelted at different temperature and different holding time is studied. The results show that heated at the temperature between liquidus and solidus, the eutectic in AlSi7Mg alloy stirred by an electromagnetic field is first remelted, and α-phase gradually evolves into spheroidal-like shape. The higher the holding temperature or the longer the holding time is, the smoother the side of α-phase turns. But if the holding temperature is too high or the holding time is too long, some liquid metal is exuded from the surface of samples, and the samples are deformed by their own gravity. The dimension of the solid phase heated from room temperature is bigger than that heated from a higher initial temperature.
Influence of heating processing on microstructure of semi-solid remelted AlSi7Mg alloy
Abstract:
The Microstructure of AlSi7Mg semi-solid alloy remelted at different temperature and different holding time is studied. The results show that heated at the temperature between liquidus and solidus, the eutectic in AlSi7Mg alloy stirred by an electromagnetic field is first remelted, and α-phase gradually evolves into spheroidal-like shape. The higher the holding temperature or the longer the holding time is, the smoother the side of α-phase turns. But if the holding temperature is too high or the holding time is too long, some liquid metal is exuded from the surface of samples, and the samples are deformed by their own gravity. The dimension of the solid phase heated from room temperature is bigger than that heated from a higher initial temperature.
Fig.3 Microstructures of AlSi7Mg alloy remelted at different holding temperatures and for same holding time (t=15 min) from higher initial temperature (a) —θ=575 ℃; (b) —θ=581 ℃; (c) —θ=587 ℃; (d) —θ=593 ℃
图4 热炉加热方式AlSi7Mg合金在不同保温温度重熔后的外观照片 (保温时间t=15 min)
Fig.4 Appearances of AlSi7Mg alloy remelted at different holding temperatures and for same holding time (t=15 min) from higher initial temperature (a) —Initial sample; (b) —θ=575 ℃; (c) —θ=581 ℃; (d) —θ=587 ℃; (e) —θ=593 ℃
Fig.6 Microstructures of AlSi7Mg alloy heated for different holding times and of same holding temperature ( θ=587 ℃) from higher initial temperature (a) —t=10 min; (b) —t=20 min; (c) —t=25 min; (d) —t=30 min
图7 随炉加热方式AlSi7Mg合金在不同保温温度重熔后的组织 (保温时间t=15 min)
Fig.7 Microstructures of AlSi7Mg alloy heated at different holding temperatures and for same holding time (t=15 min) from room temperature (a) —θ=575 ℃; (b) —θ=581 ℃; (c) —θ=587 ℃; (d) —θ=593 ℃
图8 随炉加热方式AlSi7Mg合金在不同保温时间重熔后的组织 (保温温度θ=587 ℃)
Fig.8 Microstructures of AlSi7Mg alloy heated for different holding times and at same holding temperature ( θ=587 ℃) from room temperature (a) —t=5 min; (b) —t=10 min; (c) —t=15 min; (d) —t=20 min