往复挤压对Mg-6%Si合金组织与力学性能的影响

Effects of Reciprocating Extrusion on Microstructures and Mechanical Properties of Mg-6%Si Alloy

摘要:

研究了往复挤压对铸造Mg-6%Si (质量分数,下同)合金微观组织和力学性能的影响。结果表明：往复挤压4道次后，Mg-6%Si合金的显微组织得到显著细化，粗大树枝状的初生Mg2Si相变为细小颗粒状，而汉字状的共晶Mg2Si相也变为弥散分布的点状相，且这些颗粒状的Mg2Si相均匀分布在基体中。往复挤压4道次后，Mg-6%Si合金的抗拉强度和延伸率分别提高了82.3%和810.9%。断口分析表明，往复挤压合金的断裂模式由脆性断裂转变为韧-脆性断裂。

Abstract:

Effects of reciprocating extrusion on the microstructure and mechanical properties of the as-cast Mg-6%Si alloy were studied. Results show that the microstructures of the Mg-6%Si alloy are refined markedly after reciprocating extrusion with 4 passes; the coarse dendritic primary Mg2Si phase changes into fine granules, the size of the Chinese-character-like eutectic Mg2Si phase also decreases gradually and more uniform distribution of the granular Mg2Si phase in the matrix is obtained. After reciprocating extrusion with 4 passes, the tensile strength and the elongation are increased by 82.3% and 810.9%, respectively, compared with those of the as-cast alloy. Fracture analysis shows that the fracture mode of the alloy changes from brittle fracture to ductile-brittle fracture after reciprocating extrusion