Pb-Sn对压铸AZ81镁合金组织和力学性能的影响

Effects of Pb-Sn on microstructure and mechanical properties of die casting AZ81 magnesium alloy

摘要:

向AZ81镁合金中分别加入0.5%Pb、0.5%Pb+0.5%Sn、0.5%Pb+1.0%Sn合金元素并压铸成型，研究了各成分合金的微观组织和常温、180℃力学性能。结果表明：1）AZ81-0.5Pb-1.0Sn中存在多边形Mg2Sn，主要分布在晶界；同时，Pb和Sn元素的加入在一定程度上减少了晶界上Mg17Al12的数量，有助于提高镁合金的耐中高温性能；2）室温下，压铸AZ81-0.5Pb-(0, 0.5, 1.0)Sn合金抗拉强度和屈服强度随着Sn含量的增加而提高，压铸AZ81-0.5Pb-1.0Sn的抗拉强度为211 MPa、屈服强度为150.5 MPa；3)180℃下，随着Sn含量的增加，抗拉强度和屈服强度均提高，压铸AZ81-0.5Pb-1.0Sn抗拉强度值为200.5 MPa、屈服强度为145.2 MPa；4）添加元素Pb+Sn使压铸AZ81的180℃断裂机制由塑性断裂向脆性断裂转变。

Abstract:

Based on die casting AZ81 alloy, this article focuses on the effects of adding alloying elements (0.5%Pb, 0.5%Pb+0.5%Sn、0.5%Pb+1.0%Sn) on its microstructure and mechanical properties at room temperature and 180℃. 1) In the alloy of AZ81-0.5%Pb-1.0%Sn, there was polygon Mg2Sn phase at grain boundary. In the meantime, Pb and Sn suppressed the formation of precipitation Mg17Al12 at grain boundary to a certain extent, which contributed to the medium temperature resistance. 2) At room temperature, the tensile strength and yield strength of the alloys increased with the increase of Sn. The tensile strength and yeild strength of die casting AZ81-0.5Pb-1.0Sn at room temperature were 211 MPa and 150.5 MPa, respectively. 3) At 180℃,the tensile and yeild strength increased with the increase of Sn as well. The tensile strength and yeild strength of die casting AZ81-0.5Pb-1.0Sn alloy at 180℃ were 200.5 MPa and 145.2 MPa, respectively. 4) The Pb-Sn made the fracture mechanism transferred from plasticity to brittleness.