Study On The Densification Process Of Spray-deposited 5A06 Aluminum Alloy By Wedge Pressing

As an advanced materials preparation technology,spray-deposition has shown remarkable superiority in producing large-sized alloys and metal matrix composites.However,the spray deposeted preforms usually contain a certain quantity of porosity.Besides,the oxide films on the surface of the particles lead to week metallurgic conjunction between the particles.In order to obtain an ideal structure and performance,the porous preforms need further densifying and plastical forming.In this paper,a new technology named wedge pressing was used to densify spray-deposeted 5A06 aluminium alloy,in which the large deformation can be obtained through the sum-up of local deformation and multi-step small deformation.This method can also solved the problems in traditional processing and greatly decreased the producing cost.What's more,the reserch on the wedge pressing desification rules about the large-sized spray deposeted preforms was significant It was vital not only to the further densification of the prefoums but also to the further research on plastical deforming The research was also benefit to the industrialization an the application of the spray deposeted porous materials.Firstly,the comparation study between the wedge pressing and the contour forging has shown that the transverse deforming initiated from the surface of the preforms.When the superficies reached the moulding wall,the deforming moved downwards as the high-direction deforming increased,till the moulding chamber was full of stock;the transverse deforming of the moulding pressing stock initiated from the center of the stock then surned into a drum-type.The distribution of the density and hardness of the high-direction indicated that the wedge pressing acquired a better ability of pressing penetration.Secondly,the effect of transverse deforming on the property of the wedge pressing was studied.The results showed that:The wedge pressing stock with the transverse deforming amount of 10% acquired the best performance.The highest density got the biggest rate of slope while with the amount of 30% the curve was more some special structure and performance as following:The large porosities was crushed into small or linear ones with the high-direction deformation amount of 20%;as the increasing of the high-direction deforming,the particles got a further deforming,the porosities got a further crushing,the small porosities were mergered by the large ones and the former then disappeared;when the amound reached 60%,the quantity of the porosities would obviously decrease which made the materials compact,the microstructure more uniform and the density and hardness curves more horizontal ,the relative desity could reach 99.7%,the tensile strengthσb of the as-compacted samples reached 408Mpa with the yield strengthσs teached 289Mpa and the elongation percentageδreached 13.6%.In addition,the microstructure of the wedge pressing stock under the pressing temperectureof 450℃was uniform,the porosities and the boundries of the grains basically disappeared and the conjunction between particles was great.Finally,the fracture behavior of the wedge pressing stock under different temperatures was studied.As a result,the wedge pressing under 450℃could avoid the step on the surface of the stock and...