(1. 蘭州理工大學(xué) 省部共建有色金屬先進(jìn)加工與再利用國家重點(diǎn)實(shí)驗(yàn)室，蘭州 730050；
2. 蘭州理工大學(xué) 有色金屬合金及加工教育部重點(diǎn)實(shí)驗(yàn)室，蘭州 730050)
摘 要: 半固態(tài)金屬坯料部分重熔是半固態(tài)金屬觸變成形工藝的重要技術(shù)環(huán)節(jié)，采用等溫?zé)崽幚矸▽g-6Zn-1Cu-0.5Ce鎂合金在部分重熔過程中的非枝晶組織演變過程和機(jī)理進(jìn)行研究。結(jié)果表明：在半固態(tài)重熔初始階段，Mg-6Zn-1Cu-0.5Ce合金沿晶界分布的共晶相逐漸向α-Mg基體中擴(kuò)散溶解，達(dá)到共晶熔化溫度后，剩余部分開始熔化。隨著保溫時(shí)間的進(jìn)一步延長，為了降低系統(tǒng)的界面能，顆粒將發(fā)生合并長大。其中，非枝晶顆粒的分離是由液相沿亞晶界浸滲和根部重熔兩種機(jī)制起主導(dǎo)作用。Mg-6Zn-1Cu-0.5Ce合金的最佳等溫?zé)崽幚砉に嚍楸販囟?00 ℃和保溫時(shí)間25 min，采用該工藝處理后所得非枝晶顆粒平均尺寸為57μm，形狀因子為1.16，固相率為68%。
關(guān)鍵字: Mg-6Zn-1Cu-0.5Ce鎂合金；部分重熔；半固態(tài)；非枝晶組織；演變機(jī)理
（1. State Key Laboratory of Gansu Advanced Non-ferrous Metal Materials, Lanzhou University of Technology, Lanzhou 730050, China;
2. Key Laboratory of Nonferrous Metal alloys and Processing, Ministry of Education, Lanzhou University of Technology, Lanzhou 730050, China）
Abstract:Partial remelting is the important part of semi-solid metal (SSM) ingots forming technology. The non-dendritic microstructure evolution process and mechanism of Mg-6Zn-1Cu-0.5Ce magnesium alloy during partial remelting were investigated by isothermal heat-treatment. The results indicate that the eutectic phases of Mg-6Zn-1Cu-0.5Ce alloy initial microstructure distribute on grain boundary, which gradually dissolves into α-Mg matrix due to the diffusion of the solute, and the remainder is melted when the temperature up to eutectic melted during the initial stage of partial remelting. With the heat preservation time further extending, the semi-solid particles will combine and grow up to reduce the surface energy of the system. Furthermore, the appearance of subboundary and root remelting are the predominant separation mechanisms of particles during partial remelting. The best parameters of isothermal heat treatment are 600 ℃ in holding temperature and 25 min in holding time, obtaining the semi-solid microstructure with the average partial size of 57 μm, the roundness of 1.16 and the solid fraction of 68%.
Key words: Mg-6Zn-1Cu-0.5Ce magnesium alloy; partial remelting; semi-solid; non-dendritic microstructure; evolution mechanism
