Preparation Of Al₂Cu-Al₂O₃Particles Reinforced Al Matrix By Mechanical Alloying And Spark Plasma Sintering

Al metal matrix is characterized by high specific strength, high specific stiffness andgood machinability, which have wide potential applications in military industry, aerospaceindustries and automobile fields. High-strength bulk Al2Cu and Al2O3particles reinforcedAl metal matrix were fabricated by mechanical alloying (MA) and spark plasma sintering(SPS). The effect of MA process parameters and Cu content on the phase structure andmicrostructure of the Al-Cu composite powders were investigated. In order to study phaseformability and solid solubility expansion, the thermodynamic analysis in Al-Cu systemwas studied. Meanwhile the in-situ reaction between Al and CuO during MA wereinvestigated. Finally in-situ Al2Cu-Al2O3/Al composites were synthesized by SPS process.The results showed that, in the reaction between Al and Cu, some amount of Cuatoms gradually diffused into Al matrix to form a homogeneous supersaturated Al(Cu)solid solution during the MA process. The solid solubility increased with the increase ofmilling time. For Al-Cu binary system, solid solution is the most stable phase thanamorphous phase and metal matrix according to thermodynamic calculation and DSCanalysis results.Bulk dense in-situ Al2Cu/Al composites were fabricated by sintering the alloypowders after MA for60h. The sintering pressure, displace and temperature varied by thetime. Increase the sintering pressure was favorable to the densification process of theAl2Cu/Al composites. Meanwhile, the reinforcing phase turned to become much smallerand distributed more homogeneously. As a result, the sintered composite owned highhardness value. The morphology of reinforcing phase changed along with the various Cucontents. When the Cu content was relatively low, fine grain size Al2Cu particlesdistributed more homogeneously in the metal matrix. With the increase Cu content, rodlikeAl2Cu particles appeared. Increasing the Cu content continuously, the reinforcing phase Al2Cu turned to agglomerate seriously. When the Cu content was10%, the fracturestrength of sintered sample reached611.3MPa, and its plastic strain was9.6%.In the reaction between Al and CuO, Al2O3and Al2Cu particle reinforced Al metalmatrix was fabricated by MA and SPS. During MA, Al and part CuO occurred redoxreaction during MA.