(1. 重慶大學(xué) 制造系統(tǒng)工程重慶市重點(diǎn)實(shí)驗(yàn)室， 重慶 400044；
2. 重慶大學(xué) 機(jī)械工程學(xué)院， 重慶 400044；
3. 重慶大學(xué) 職業(yè)技術(shù)學(xué)院， 重慶 400044)
摘 要: 研究了ZL112Y壓鑄鋁合金在半固態(tài)壓鑄成形過程中的組織演變過程。 觀察了原始料坯、半固態(tài)重熔后快速水淬的料坯、 壓鑄機(jī)壓室內(nèi)的沖頭料坯以及壓鑄模內(nèi)的內(nèi)澆口和半固態(tài)壓鑄零件中不同部位的固相α 組織的形貌， 同時(shí)采用定量金相的方法分析了這些部位的固相α 組織的圓形度、 粒子平均直徑和單位面積粒子個(gè)數(shù)等參數(shù)。 結(jié)果表明： 半固態(tài)重熔過程使原始料坯中的α 枝晶組織變成節(jié)桿狀和球團(tuán)狀組織， 轉(zhuǎn)變的原因是枝晶熔斷機(jī)制； 重熔后料坯在壓室內(nèi)的運(yùn)動(dòng)過程使半固態(tài)料坯中的α 粒子尺寸的不均勻性得以消除， 同時(shí)使殘留的枝晶得以進(jìn)一步的分離細(xì)化； α 相均勻化和細(xì)化了的半固態(tài)漿料進(jìn)入鑄型后液相更容易到達(dá)鑄件遠(yuǎn)端， 液相和固相充型是2個(gè)不同的過程， 液相的充型速率要大于固相。
關(guān)鍵字: 組織演變； 半固態(tài)壓鑄； ZL112Y壓鑄鋁合金
（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
