摘要
A new and effective semisolid slurry preparation process with air-cooled stirring rod(ACSR)is reported,in which the compressed air is constantly injected into the inner cavity of a stirring rod to cool the melt.The slurry of a newly developed high thermal conductivity Al?8Si alloy was prepared,and thin-wall heat dissipation shells were produced by the ACSR process combined with a HPDC machine.The effects of the air flow on the morphology ofα1-Al particles,mechanical properties and thermal conductivity of rheo-HPDC samples were studied.The results show that the excellent slurry of the alloy could be obtained with the air flow exceeding3L/s.Rheo-HPDC samples that were produced with the air flow of5L/s had the maximum UTS,YS,elongation,hardness and thermal conductivity of261MPa,124MPa,4.9%,HV99and153W/(m·K),respectively.Rheo-HPDC samples show improved properties compared to those formed by HPDC,and the increasing rates of UTS,YS,elongation,hardness and thermal conductivity were20%,15%,88%,13%and10%,respectively.
报道了一种新颖、高效的采用气冷搅拌杆制备半固态浆料的工艺,该工艺通过将压缩空气不断注入到搅拌杆内腔来冷却熔体。采用该工艺制备了一种新近研发的高导热Al-8Si合金半固态浆料,并将该工艺与高压铸造机结合生产出一种无线基站用薄壁散热壳体件。研究了气体流量对初生晶粒的形貌、流变压铸件的力学性能及导热系数的影响。结果表明:当气体流量超过3 L/s时,采用该工艺可以制备出优质的半固态浆料。当气体流量为5 L/s时,流变压铸件的力学性能和导热系数最高,分别为抗拉强度261 MPa,屈服强度124 MPa,伸长率4.9%,显微硬度HV 99和导热系数153 W/(m·K)。相比于传统压铸件,采用气冷搅拌杆流变压铸工艺生产的铸件力学性能和伸长率大大提高,其抗拉强度、屈服强度、伸长率、显微硬度和导热系数的增长率分别为20%、15%、88%、13%和10%。
基金
Project (2013B091300016) supported by the Department of Science and Technology of Guangdong Province,China
