A356 合金半固態(tài)組織的影響
( 1. 南昌大學(xué) 材料科學(xué)與工程學(xué)院，南昌 330047;
2. 南昌大學(xué) 機(jī)電工程學(xué)院，南昌 330029)
摘 要: 利用開(kāi)發(fā)的低轉(zhuǎn)速輸送管控制澆注工藝制備了A356合金半固態(tài)組織，從不同澆注溫度、不同轉(zhuǎn)動(dòng)速度下晶核的來(lái)源和不同結(jié)晶器冷卻強(qiáng)度下游離晶演變的2個(gè)角度，結(jié)合凝固微觀組織模擬技術(shù)分析了非枝晶組織的形成與演變規(guī)律。結(jié)果表明：適當(dāng)?shù)牡蜏貪沧⒑洼斔凸苻D(zhuǎn)速可極大地提高有效形核數(shù)目，降低熔體的冷卻強(qiáng)度有利于初生相呈球形生長(zhǎng)；晶粒周?chē)苜|(zhì)擴(kuò)散層的疊加影響著液/固界面處引起界面失穩(wěn)的濃度梯度，進(jìn)而影響初生相的生長(zhǎng)形態(tài)。
關(guān)鍵字: 漿料制備；控制澆注；非枝晶；微觀組織模擬
microstructure of A356 alloy
（ 1. School of Materials Science and Engineering,
Nanchang University, Nanchang 330047, China;
2. School of Mechanical and Electronic Engineering,
Nanchang University, Nanchang 330029, China）
Abstract: Semi-solid slurry of A356 alloy was produced by a controlled pouring process with a rotating duct. Nucleation behavior and morphology evolution of primary phase under different pouring temperatures were investigated. Rotating speeds of the duct and cooling intensity of crucible were studied. The formation of non-dendrite was analyzed through experiments and microstructure simulation technique. The results show that appropriate combination between pouring temperature and rotating speed of duct can significantly improve effective nucleation rate, decreasing the cooling intensity of the melt metal can give rise to a transition of the growth morphology from dendritic to rosette and to spheroid. Results from simulations indicate that the overlapping diffusion fields from adjacent growing crystals can influence the morphology of crystal by influencing the concentration gradients that can cause instabilities at solid/liquid interface.
Key words: slurry preparation; controlled pouring; non-dendrite; microstructure simulation
