采用等通道转角挤压(equal channel angular pressing,ECAP)方法成功挤压了Mg-3Sn-0.5Mn合金,采用OM和TEM观察了ECAP过程中合金微观组织和晶粒尺寸的变化,测试了ECAP后Mg-3Sn-0.5Mn合金的力学性能与腐蚀性能,通过XRD观察了ECAP变形后的织构取向变化。结果显示,ECAP后得到了超细晶Mg-3Sn-0.5Mn合金组织,在320 ℃下经过4道次挤压后平均晶粒尺寸细化到了1.65 μm,局部晶粒细化到了0.80 μm,晶粒细化是剧烈塑性变形与再结晶共同作用的结果。4道次变形后,延伸率从22.2%上升到58.6%,抗拉强度从242.8 MPa下降到195.6 MPa,延伸率提高了约3倍,强度略有下降。ECAP后的Mg-3Sn-0.5Mn合金织构择优取向发生了显著改变,这种变化有利于滑移系的开动,提高了材料的塑性,但对强度有一定的不利影响。ECAP后的Mg-3Sn-0.5Mn合金力学性能受到改变的织构择优取向和细晶强化的共同影响。

Mg alloy has attracted researchers' attention as applied for novel biomedical material because of its super corrosion property and well biocompatibility. Ultra-fine grain (UFG) Mg alloy has certain advantages in the development of medical devices because of its good plasticity and corrosion resistance. Equal channel angular pressing (ECAP) was performed on Mg-3Sn-0.5Mn alloy successfully. The microstructure and grain size were observed and measured by OM and TEM. The mechanical property was tested by microhardness and tensile test, the texture oriented was experimented by XRD, and the corrosion property was tested by electrochemical experiment. After 4 passes ECAP at 320 ℃, the average grain size of Mg-3Sn-0.5Mn alloy reached 1.65 μm, and local grain size reached 0.8 μm. The grain refinement was caused by severe plastic deformation and recrystallization. The elongation increased from 22.2% to 58.6%, the tensile strength decreased from 242.8 MPa to 195.6 MPa after 4 passes deformation. The mechanical tests showed an improvement in the elongation after 4 passes, which were about 3 times higher than in the as-extruded sample, whereas the tensile strength decreased slightly. The texture of Mg-3Sn-0.5Mn alloy changed obviously which contributed to the actuating of the slip system. This change of texture contributed to the improvement of fracture elongation and decrease of tensile strength. The mechanical property of Mg-3Sn-0.5Mn alloy after ECAP was affected by the texture orientation and grain strengthening.