(1. 上海交通大學(xué) 輕合金精密成型國家工程研究中心，上海 200240；
2. 上海交通大學(xué) 金屬基復(fù)合材料國家重點(diǎn)實(shí)驗(yàn)室，上海 200240)
摘 要: 在應(yīng)變速率為0.001 5~1.5 s−1、溫度為315 ℃條件下，在Gleeble−3500熱模擬機(jī)上對不同準(zhǔn)晶含量(體積分?jǐn)?shù))Mg-Zn-Gd-Y合金的高溫?zé)釅嚎s變形特性進(jìn)行研究。研究變形過程中合金的真應(yīng)力與應(yīng)變關(guān)系，通過選取合理模型描述了315 ℃時合金的流變應(yīng)力與應(yīng)變速率的關(guān)系，并對不同準(zhǔn)晶含量的合金在不同變形量下的微觀組織進(jìn)行觀察。結(jié)果表明：高應(yīng)變速率下不同準(zhǔn)晶含量的Mg-Zn-Gd-Y合金的真應(yīng)力—應(yīng)變曲線差異較大，高準(zhǔn)晶含量Mg-Zn-Gd-Y合金表現(xiàn)出較好的塑性變形能力；應(yīng)變速率的變化對高準(zhǔn)晶含量Mg-Zn-Gd-Y合金的流變應(yīng)力影響較大，且Mg-Zn-Gd-Y合金變形后晶粒隨應(yīng)變速率的增大而減小；在塑性變形過程中，準(zhǔn)晶可以促進(jìn)Mg-Zn-Gd-Y合金的動態(tài)再結(jié)晶，同時也有利于孿晶的生成。
關(guān)鍵字: Mg-Zn-Gd-Y合金；準(zhǔn)晶；流變應(yīng)力；動態(tài)再結(jié)晶
different contents of quasicrystal
（1. National Engineering Research Center of Light Alloy Net Forming，Shanghai Jiao Tong University,
Shanghai 200240, China;
2. State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China）
Abstract: Hot compression tests of Mg-Zn-Gd-Y alloys with different volume fractions of quasicrystal were performed on Gleeble−3500 at strain rate range of 0.001 5−1.5 s−1 and constant deformation temperature of 315 ℃. The relationship between the true stress and true strain of the Mg-Zn-Gd-Y base alloys was studied in the tests, and a proper constitutive equation was selected to describe the relation between the flow stress and strain rate. The microstructures of the investigated alloys were also studied in the hot-compression procedure. The results show that the true stress vs true strain curves vary with different volume fractions of quasicrystal at higher strain rate, the alloys with higher volume fraction of quasicrystal exhibit better formability. The strain rate change has a more significant impact on the flow stress of Mg-Zn-Gd-Y alloys with higher volume fraction of quasicrystal. The average grain sizes of the transformed Mg-Zn-Gd-Y alloys decrease with increasing strain rate. The dynamic recrystallization of Mg-Zn-Gd-Y alloys can be promoted by quasicrystal during deformation. At the same time, the quasicrystal also favors the formation of deformation twins.
Key words: Mg-Zn-Gd-Y alloys; quasicrystal; flow stress; dynamic recrystallization
