顯微組織與力學(xué)性能
(1. 湖南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410082；
2. 北京航空材料研究院，北京 100095)
摘 要: 利用攪拌鑄造−熱擠壓工藝制備SiCp/2024鋁基復(fù)合材料板材，研究該復(fù)合材料鑄態(tài)、熱擠壓態(tài)和熱處理態(tài)的顯微組織及力學(xué)性能。結(jié)果表明：SiC顆粒較均勻地分布于鑄錠中，大部分SiC顆粒沿晶界分布，少數(shù)顆粒分布于晶內(nèi)，晶界粗大的第二相呈非連續(xù)狀分布；復(fù)合材料經(jīng)熱擠壓變形后，顯微孔洞等鑄造缺陷明顯消除，破碎的晶界第二相及SiC顆粒沿?zé)釘D壓方向呈流線分布，復(fù)合材料的強度和塑性顯著提高；對熱擠壓板材進行(495 ℃，1 h)固溶處理+(177 ℃，8 h)時效處理后，其抗拉強度達430 MPa，此時的主要析出強化相為S′(Al2CuMg)；熱擠壓變形有利于改善SiC顆粒與基體合金的界面結(jié)合，熱處理SiCp/2024鋁基復(fù)合材料的主要斷裂方式為基體合金的延性斷裂、SiC顆粒斷裂和SiC/Al的界面脫粘。
關(guān)鍵字: 鋁基復(fù)合材料；攪拌鑄造；熱擠壓；顯微組織；力學(xué)性能
matrix composite synthesized by stir casting
（1. College of Materials Science and Engineering, Hunan University, Changsha 410082, China;
2. Beijing Institute of Aeronautical Materials, Beijing 100095, China）
Abstract:SiCp/2024 aluminum matrix composite plates were prepared by stir casting and hot extrusion process. The microstructures and mechanical properties of the as-cast, as-hot extruded and as-heat treated SiCp/2024 aluminum matrix composite were investigated. The results show that SiC particles distribute uniformly in the as-cast composite ingot, most of which distribute along the grain boundaries, few locate inside the grains, the coarse secondary phases along the grain boundary distribute in discontinuity. After the hot extrusion process, most of the casting defects in the as-cast composite are eliminated. The broken eutectic phases and SiC particles distribute along the flowing direction of the metal plastic. The strength and ductility of SiCp/2024 aluminum matrix composite increase obviously after hot extrusion. Under the condition of (495 ℃, 1 h)+(177 ℃, 8 h), the strength of the as-extruded composite plates can reach 430 MPa, S′(Al2CuMg) phase is the main precipitate at this stage. The tensile fracture surface results show that the hot extrusion deformation is helpful to improve the bonding of the SiC/Al interface. The main fracture manner of SiCp/2024 aluminum matrix composite after heat treatment is ductile failure of the alloy matrix, SiC fracture and debonding of the SiC/Al interface.
Key words: aluminum matrix composite; stir casting; hot extrusion; microstructures; mechanical properties
