元素钇对Mg-9Li-3Al-2Sr合金组织及拉伸性能的影响

摘要

采用对掺法制备了铸态 Mg-9Li-3Al-2Sr-xY(x＝0,2．5)合金,研究了元素钇对合金组织和拉伸性能的影响.结果表明：Mg-9 Li-3 Al-2 Sr合金由α-Mg、β-Li、Al4 Sr相组成,Al4 Sr相主要分布在β-Li相中；Mg-9Li-3Al-2Sr-2．5Y合金主要由α-Mg、β-Li、Al4 Sr和Al2 Y相组成,Al4 Sr相主要分布在β-Li 相中,而 Al2 Y 相则弥散分布在基体中；与 Mg-9Li-3Al-2Sr 合金相比,Mg-9Li-3Al-2Sr-2．5Y合金的抗拉强度变化不大,但伸长率提高了17．3％；Mg-9Li-3Al-2Sr 合金的断裂机制为典型的沿晶断裂,而Mg-9 Li-3 Al-2 Sr-2．5 Y合金的断裂机制则是以脆性断裂为主,并伴有韧窝的混合型断裂.%As-cast Mg-9Li-3Al-2Sr-xY (x=0,2.5 )alloys were prepared through mixture method,the influences of yttrium element on microstructure and tensile properties of Mg-9Li-3Al-2Sr alloy were studied.The results show that Mg-9Li-3Al-2Sr alloy was mainly composed ofβ-Li,α-Mg and Al4 Sr phases,and Al4 Sr phase was mainly distributed inβ-Li phase;Mg-9Li-3Al-2Sr-2.5Y alloy was mainly composed ofβ-Li,α-Mg,Al4 Sr and Al2 Y phases,Al4 Sr phase mainly distributed inβ-Li phase and Al2 Y phase diffusely distributed in the matrix.Compared with Mg-9Li-3Al-2Sr alloy,the tensile strength of Mg-9Li-3Al-2Sr-2.5Y alloy changed a little,but elongation increased by 17.3%.Fracture mechanic of Mg-9Li-3Al-2Sr alloy mainly was intergranular fracture,while the fracture mode of Mg-9Li-3Al-2Sr-2.5Y alloy mainly was a mixture of main brittle fracture and dimple characteristics.