(1. 內(nèi)蒙古科技大學(xué) 材料與冶金學(xué)院，包頭 014010；
2. 重慶大學(xué) 材料科學(xué)與工程學(xué)院，重慶 400044；
3. 內(nèi)蒙古第一機(jī)械集團(tuán)有限公司 第十分公司，包頭 014030；
4. 重慶大學(xué) 國(guó)家鎂合金工程技術(shù)研究中心，重慶 400044)
摘 要: 通過(guò)OM、SEM、XRD和拉伸實(shí)驗(yàn)研究3種典型的Mg-Li-Al合金的鑄態(tài)和擠壓態(tài)組織及力學(xué)性能。結(jié)果表明：隨著Li含量的增加，合金的結(jié)構(gòu)從密排六方向體心立方轉(zhuǎn)變，合金的鑄態(tài)組織隨之發(fā)生改變。經(jīng)過(guò)250 ℃擠壓處理后，Mg-5Li-1Al和Mg-9Li-1Al合金的晶粒沿?cái)D壓方向呈方向性排列，Mg-14Li-1Al合金由均勻的等軸晶(再結(jié)晶晶粒)組成。隨著Li含量的增加，擠壓態(tài)合金板材的屈服強(qiáng)度逐漸增大，其中擠壓態(tài)Mg-9Li-1Al合金板材的綜合力學(xué)性能最佳(屈服強(qiáng)度達(dá)到149 MPa，伸長(zhǎng)率達(dá)到25%)。
關(guān)鍵字: 鎂鋰合金；擠壓；顯微組織；力學(xué)性能
（1. School of Materials and Metallurgy, Inner Mongolia University of Science and Technology, Baotou 014010, China;
2. College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China;
3. The Tenth Sub-company, Inner Mongolia First Machinery Group Corporation, Baotou 014030, China;
4 National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044, China）
Abstract:The as-cast and extruded microstructures and mechanical properties of three kinds of Mg-Li-Al alloys were studied by optical microscopy, SEM, XRD and tensile test. The results show that, with the increase of lithium additions, the crystal structure transforms from close-packed hexagonal (HCP) structure to body centered cubic (BCC) structure, and the as-cast microstructures of the Mg-Li-Al alloys change correspondingly. After extrusion at 250℃, the grain of Mg-5Li-1Al and Mg-9Li-1Al alloys are arranged along the extruded direction, but the microstructures of Mg-14Li-1Al alloy sheet consist of equiaxed crystals. The yield stress of the extruded alloys is improved gradually with the increase of lithium content. The extruded Mg-9Li-1Al alloy obtains the optimal mechanical properties (the yield stress and elongation are 149 MPa and 25%, respectively), along the transverse direction.
Key words: Mg-Li alloy; extrusion; microstructure; mechanical property
