Study On Preparation And Properties Of Powder Metallurgy Al-Cu-Mg-Si Material

Powder metallurgy(PM) aluminum alloys possess an array of advantages of high material utilization, low cost and good comprehensive performance, including near-net shaping and low density of aluminum. Aluminum alloys has become one of the main directions of automobile lightweight, and has a broad application prospect. In this thesis, PM AlCuMgSi material was researched which were used in automotive, and a kind of powder raw material has been developed independently. PM aluminium alloy was prepared in the conventional method, whose performance meets the requirenments of practical application, so as to satisfy the increasing of domestic auto lightweight material needs.In summary, The main conclusions can be drawn as follows:(1) Apparent density of the developed powder of Al-3.8Cu-1.0Mg-0.75 Si powder is 1.46 g/cm3, and liquidity is 30 s/50 g.The particle size distribution range is wide, witch has good performance compared with the powder produced by United States AMB2712;(2) According to the result of differential thermal and weightlessness analysis, the best sintering process is formulated. In the high-purity nitrogen atmosphere at a heating rate of 5℃/min from room temperature to 400℃, heat 60 min, then heating rate 5℃/min was heated to 590℃, holding 60 min, furnace cooling to 200℃, then air cooled to room temperature.(3) After pressed by 350 MPa and liquid phase sintering in nitrogen atmosphere, material density is 98.9%, the average HB is 64, tensile strength get to 207 MPa, elongation is 2.1%. The good performance can meet the demands of practical application;(4) After aging treatment, which quenching treatment of 30 min at 500℃, water quenching and then continue to 24 h at 190℃,’ hardness get to HB129, tensile strength is 336 MPa. Compared with the sintering materials, performance of aged materials is greatly increased;(5) Adding Cu in the aluminum alloy(elements or alloy powder), due to the generation of Al-Cu mesophase promoted liquid phase sintering, material sintering density increased by 5%, HB increased by 50%, and tensile strength was greatly improved; Adding Mg(elements or alloy powder) can destroy the alumina membrane, so increased sintering density by 10%. HB increased by 40% and its tensile strength increased about doublly; When Sn was added in the aluminum alloy, the tensile strength can be improved. Not only Sn can promotes the sintering activation, and dissolve in the Al substrate firstly compared Cu, which make the liquid phase last longer, so to promote the sintering density and improve the material performance.