(1. 重庆大学 制造系统工程重庆市重点实验室， 重庆 400044；
2. 重庆大学 机械工程学院， 重庆 400044；
3. 重庆大学 职业技术学院， 重庆 400044)
摘 要: 研究了ZL112Y压铸铝合金在半固态压铸成形过程中的组织演变过程。 观察了原始料坯、半固态重熔后快速水淬的料坯、 压铸机压室内的冲头料坯以及压铸模内的内浇口和半固态压铸零件中不同部位的固相α 组织的形貌， 同时采用定量金相的方法分析了这些部位的固相α 组织的圆形度、 粒子平均直径和单位面积粒子个数等参数。 结果表明： 半固态重熔过程使原始料坯中的α 枝晶组织变成节杆状和球团状组织， 转变的原因是枝晶熔断机制； 重熔后料坯在压室内的运动过程使半固态料坯中的α 粒子尺寸的不均匀性得以消除， 同时使残留的枝晶得以进一步的分离细化； α 相均匀化和细化了的半固态浆料进入铸型后液相更容易到达铸件远端， 液相和固相充型是2个不同的过程， 液相的充型速率要大于固相。
关键字: 组织演变； 半固态压铸； ZL112Y压铸铝合金
（1. Key Lab of Manufacturing System Engineering of Chongqing,
Chongqing University, Chongqing 400044, China;
2. College of Mechanical Engineering, Chongqing University,
Chongqing 400044, China;
3. College of Occupation and Technology,
Chongqing University, Chongqing 400044, China）
Abstract:Structural evolutions of ZL112Y die cast alloy in procedures of semi-solid die-casting were investigated. The structures of solid α phase of original billet, semi-solid remelting billet after quenching in water, pierce block in the chamber of die-casting machine, ingate block in die cast mould and specimens at different locations in a semi-solid die cast component were observed. Meanwhile, the circularity of α particles, mean equivalent diameter of α particle, volume fraction of α solid phase, numbers of α particles were measured by the quantity analysis of metallography. The results show that, 1)dendritical colonies of α phase in original billet change into isolated grains with forms of nodules and granule, owing to the dendrite fusing-off mechanism of alloys at heating up to semi-solid temperatures, and the semi-solid billet has a thixotropy property and can be used to form component in die casting; 2)the motion of the billet in squeezing chamber in die cast machine minimizes heterogeneity of sizes of α particles and refines dendrites further that are remained during semi-solid remelting; and 3)liquid phase more easily arrives at the end of the component than solid α particle as homogenized and refined semi-solid slurry enters the cavity of die-casting mould, therefore, in the location in a component far from ingate the number of solid α particles is less than that near ingate.
Key words: structural evolution; semi-solid die-casting; ZL112Y die cast aluminium alloy
