引晶法制备半固态A356铝合金浆料(英文)

开发一种半固态金属浆料制备技术,即引晶法,研究工艺参数对半固态A356铝合金浆料组织的影响,讨论球状初生α(Al)晶粒的形成机制和形貌控制。结果表明:当制备浆料为4kg、引晶尺寸为10mm、加入量为3.5%、倾倒温度为611-617°C时,半固态浆料中初生α(Al)晶粒的平均直径可达40-75μm,形状因子可达0.82-0.89。当引晶尺寸为10mm、倾倒温度为613°C、加入量为2%-4%时,初生α(Al)晶粒的平均直径可达45-82μm,形状因子可达0.78-0.88。倾倒温度的降低或者引晶加入量的适当增加,可以改善初生α(Al)晶粒的组织。当QR=QA、Rh=Rc时,只要倾倒温度适宜就可以制备优质半固态浆料。引晶熔化时产生的枝晶碎块是半固态浆料中初生α(Al)晶粒的直接来源,形成的温度过冷区也有利于异质形核。

Preparation of semi-solid A356 Al-alloy slurry by introducing grain process

A preparation technology of semi-solid metal slurry introducing grain process(IGP) was developed.The effects of processing parameters on the microstructures of the semi-solid A356 Al-alloy slurries were investigated,and the formation mechanism and morphology controlling of the spherical primary α(Al) grains were discussed.The results show that when the preparing slurry is 4 kg,IG size is 10 mm,dosage is 3.5% and dumping temperature(DT) is 611-617 °C,the mean diameter of the primary α(Al) grains in the semi-solid slurries can reach 40-75 μm and the shape factor can reach 0.82-0.89.When the IG size is 10 mm,DT is 613 °C and dosage is 2%-4%,the mean diameter can reach 45-82 μm and the shape factors can reach 0.78-0.88.With decreasing DT or increasing dosage properly,the primary α(Al) grain morphology is better.When Q R =Q A and R h =R c,as long as the DT is suitable,excellent semi-solid slurry can be produced.As a result of the IG melting,a large amount of dendritic fragments can become the direct source of the primary α(Al) grains.Meanwhile,many undercooled areas are formed,where abundant primary α(Al) grains are multiplied by heterogeneous nucleation.