摘要
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。
CNTs/7075 metal matrix composites were fabricated by friction stir processing( FSP),then solution and aging heat treatments were carried out for the composites,and the effect of solution temperature on microstructure and mechanical properties of the CNTs/7075 composites were investigated. The results show that coarse secondary phase particles in base metal are broken during FSP. With the increase of solution temperature,the fine particles dissolve into the base metal gradually,and many strengthening phase particles reprecipitate after aging treatment due to increasing the supersaturation of the alloying elements in the base metal. The XRD analysis shows that Cu Al_2 phase is dissolved into the base metal in solution treatment to form supersaturate solid solution,and then the η phase( MgZn_2)and S phase( Al_2CuMg) separate out in the following aging treatment. Moreover,with the increase of solution temperature,the tensile strength and elongation of the CNTs/7075 composites first increase and then decrease. When the solution temperature is 470 ℃,the tensile strength has a maximum value of 550 MPa,and which is higher than that of the base metal. Also,the elongation reaches up to3. 4%. From the fracture analysis,the failures present a brittle cleavage fracture.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2016年第S1期17-21,共5页
Transactions of Materials and Heat Treatment
基金
国家自然科学基金(51565041
51365044
51465044)
江西省教育厅科研项目(GJJ150710)
