(1. 華南理工大學(xué) 機(jī)械與汽車工程學(xué)院，廣州 510640；
2. 華南理工大學(xué) 國(guó)家金屬材料近凈成形工程技術(shù)研究中心，廣州 510640)
摘 要: 采用等通道轉(zhuǎn)角擠壓(ECAP)工藝在573 K溫度下以Bc路徑對(duì)雙相合金Mg-10.73Li-4.49Al-0.52Y進(jìn)行 1~6道次擠壓變形，對(duì)變形合金進(jìn)行顯微組織觀察、掃描電鏡分析、X射線衍射測(cè)試和應(yīng)變速率為1.5×10−3 s−1的室溫拉伸實(shí)驗(yàn)。結(jié)果表明：該合金由(α+β)相組成，變形后晶粒沿著與擠壓方向成30°~45°角且呈拉長(zhǎng)的流線狀，隨擠壓道次的增加，晶粒不斷細(xì)化，其析出相Al2Y顆粒也隨道次的增加沿晶粒拉長(zhǎng)的方向均勻化和細(xì)化。合金原始鑄態(tài)無織構(gòu)，1道次變形后β相的主滑移面{110}晶面織構(gòu)強(qiáng)度最高，變形3道次和6道次后該晶面織構(gòu)強(qiáng)度相對(duì)1道次的下降，織構(gòu)向周圍移動(dòng)。變形到3道次，室溫下抗拉強(qiáng)度從鑄態(tài)的137.5 MPa提高到最大值166.4 MPa；4道次后，強(qiáng)度有一定程度下降。斷口分析表明，經(jīng)6道次變形后斷口呈典型的延性斷裂特征，存在更多的韌窩，并獲得較大的室溫伸長(zhǎng)率(83%)。
關(guān)鍵字: 鎂鋰合金；等通道轉(zhuǎn)角擠壓；顯微組織；力學(xué)性能；織構(gòu)
（1. School of Mechanical and Automotive Engineering, South China University of Technology,
Guangzhou 510640, China;
2. National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials,
South China University of Technology, Guangzhou 510640, China）
Abstract:The microstructure evolution and mechanical properties of Mg-10.73Li-4.49Al-0.52Y two-phase magnesium alloy processed by equal channel angular pressing (ECAP) from 1 pass to 6 passes at 573 K using route Bc were analyzed by OM, SEM and XRD, and the mechanical properties were tested at room temperature with strain rate of 1.5×10−3 s−1. The results indicate that the magnesium alloy grains consist of α phase and β phase which are elongated to be streamline at an angle of 30°−45° to the extrusion direction after ECAP, and the initial large and disperse phases of Al2Y are refined and homogenized as the extrusion pass increases. After 1 pass, non-oriented texture of the as-cast alloy exhibits the strongest texture on the main crystal {110} of β phase; after 3 and 6 passes, the texture intensity declines compared with that of 1 pass deformation, and their texture moves to periphery. After 3 passes, the tensile strength increases to the maximum of 166.4 MPa from 137.5 MPa of the as-cast at room temperature. After 4 passes, the tensile strength decreases a little. The fracture surfaces show that the fracture mode of the 6-pass ECAPed alloy shows typical ductile fracture and more dimples, and its elongation is up to 83%.
Key words: Mg-Li alloy; equal channel angular pressing (ECAP); microstructure; mechanical property; texture
