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采用搅拌摩擦加工(FSP)方法制备了CNTs/7075铝基复合材料,并对其进行固溶时效热处理,研究固溶温度对CNTs/7075组织和力学性能的影响。通过微观组织观察发现,母材中大颗粒的二次相在FSP中被搅碎,随固溶温度提高,被搅碎的细小的二次相逐渐回溶至基材中,且由于回溶后基体合金元素过饱和度增大,复合材料在时效过程中弥散析出的沉淀相数量增多。复合材料中的CuAl_2在固溶过程中回溶入基体中形成过饱和固溶体,在随后时效过程中析出η相(MgZn_2)以及少量S相(Al_2CuMg)。CNTs/7075复合材料的抗拉强度和伸长率随固溶温度升高先上升后下降,当固溶温度为470℃时,抗拉强度相对较高,达到550 MPa,高于母材,伸长率为3.4%,表现为脆性解理断裂。
The CNTs / 7075 aluminum matrix composites were prepared by friction stir processing (FSP) method and the solution heat treatment was carried out to study the effect of solution temperature on the microstructure and mechanical properties of CNTs / 7075. Through the microstructure observation, it was found that the secondary phase of the large particles in the parent metal was broken in the FSP, the fine secondary phase that was crushed was gradually dissolved back into the substrate with the increase of the solution temperature, and after the solution was dissolved The supersaturation of the matrix alloying elements increases, and the amount of precipitates dispersed in the composites increases during the aging process. In the composite, CuAl_2 is dissolved into the matrix to form a supersaturated solid solution, and η phase (MgZn_2) and a small amount of S phase (Al_2CuMg) precipitate during subsequent aging. Tensile strength and elongation of CNTs / 7075 composites first increase and then decrease with the increase of solution temperature. When the solution temperature is 470 ℃, the tensile strength of CNTs / 7075 composites is relatively high, reaching 550 MPa, The rate of 3.4%, manifested as brittle cleavage fracture.