添加Cu和T6下Mg2Si/Al复合材料的组织与性能

采用铸造法制备原位自生亚共晶Al-10Mg₂Si复合材料,研究Cu和T6热处理对该复合材料组织与力学性能的影响。结果表明:适量Cu的添加能显著减小共晶Mg₂Si相晶粒尺寸,使其晶体结构由粗大的长条状和汉字状转变为细小的条状和纤维状;同时使针状的β-Al₅Fe Si相转变为细小的不规则富Cu颗粒。经T6热处理后,质量分数为1.5%的Cu复合材料中的共晶Mg₂Si相完全球化。质量分数为1.5%的Cu添加同时提高了材料铸态下的抗拉强度(R_m)、屈服强度(R_p0.2)和伸长率(A),达317、169 MPa和2.3%,比未添加Cu提高了42.2%、24.3%和53.3%;经T6热处理的R_m和R_p0.2值分别增至332、181 MPa,而A值保持不变。同时,材料由脆性断裂完全转变为韧性断裂。

Microstructure and properties of Mg2Si/Al composite with Cu and T6

In-situ hypoeutectic Al-10Mg₂Si composites were prepared by metal mold casting.The effects of Cu and T6 heat treatment on microstructure and mechanical properties of composites were studied.The results show that the addition of appropriate amount of Cu can significantly reduce the grain size of eutectic Mg₂Si phase and change its crystal structure from coarse long strip and Chinese character to fine strip and fiber.At the same time,the needle-likeβ-Al₅Fe Si phases transform into fine and irregular Cu-rich particles.After T6 heat treatment,the eutectic Mg₂Si phase in the material containing 1.5%Cu is completely spheroidized.The tensile strength(R_m),yield strength(R_p0.2)and elongation(A)of the material with 1.5%Cu addition increase to 317 MPa,169 MPa and 2.3%,which are 42.2%,24.3%and 53.3%higher than those without Cu addition,respectively.After T6 heat treatment,R;and R;increase to 332 MPa and 181 MPa,respectively,while A remain unchanged.The brittle fracture completely transforms into ductile fracture.