Research On Interface Structure And Mechanical Properties Of Aluminum Matrix Composite Reinforced By Continuous Titanium Alloy Wire

Aluminum alloys are widely used in all professions,including aerospace,rail transit,automotive industry and construction due to their low density,high corrosion resistance,high specific strength.Extrusion forming is the main method for the production of aluminum alloy profiles.To improve further the performance of aluminum alloy profiles along the extrusion direction,a new extrusion process for continuous fiber-reinforced aluminum-based composite materials has been proposed,where the high-performance fibers are embedded into the aluminum alloy matrix,so the extruded profiles could obtain better mechanical properties,which has attracted wide attention.The extrusion process of the continuous fiber-reinforced aluminum-based composite profile is a process that the aluminum matrix passes through a specific shunt die under the action of the extrusion rod and then the matrix is combined with the reinforced fiber which passes through the feeding plate under high temperature as well as high pressure.On the one hand,in this process,the Al/Al interface will be formed on the surface of the profile due to the multi-strand metal flowing into the welding chamber after shunting,along with the solid fusion and microstructure reorganization of the material;on the other hand,during the extrusion process of the composite material,the aluminum alloy matrix contacts with the titanium alloy wire,and the elements of the two materials will diffuse under the action of high temperature and high pressure,thus forming the Al/Ti interface.The extrusion ratio,fiber diameter and other process parameters have an important influence on the interface structure and mechanical properties of the profile.Therefore,it is of great significance to research the influence of extrusion ratio and fiber diameter on the interface structure and mechanical properties of the profile.It has important engineering application value for the reasonable formulation of the profile extrusion process.In this paper,numerical simulation and experimental methods were used to study the material flow behavior of aluminum-based composite reinforced by continuous titanium wire with different extrusion ratios and diameters during extrusion.The influence of extrusion ratio and fiber diameter on the stress-strain state of matrix material and reinforced fiber was analyzed,and the intrinsic relationship between extrusion ratio and fiber diameter to the interface structure as well as mechanical properties of composite profiles was revealed.The main work and conclusions are as follows:(1)Based on the established finite element model of fiber-reinforced aluminumbased composite extrusion,the flow behavior,equivalent strain field,equivalent stress field,displacement field,temperature field,velocity field and other physical fields of continuous fiber-reinforced aluminum-based composite material during extrusion progress under different extrusion ratios and fiber diameters were studied.(2)Three sets of extrusion die for continuous fiber-reinforced aluminum-based composites were independently designed,and a series of fiber-reinforced aluminumbased composites were obtained.It was found that the Al/Ti interface of the profile with the extrusion ratio of 14.14 was poor,and there were debonding gaps where the cracks initiated and propagated along the aluminum matrix,while the Al/Ti interface of the profile with the extrusion ratio of 18.85 was tightly bonded and had no obvious defects.(3)With increasing fiber diameter,the bonding state of the Al/Ti interface became worse.When the titanium wire diameters were 1.5mm and 2mm,the aluminum alloy grains at the Al/Ti interface were strongly sheared in the welding room,which was easy to form the strong shear texture,but the degree of recrystallization of the aluminum alloy matrix was significantly weakened.(4)The mechanical properties of composite profiles were significantly improved by the reinforced fiber.The larger the diameter of the fiber was,the better the mechanical properties of the profile were.However,due to the difference in physical properties between the aluminum alloy and the titanium alloy wire,with increasing fiber diameter,the debonding gap of the Al/Ti interface increased accordingly,and the lamellar tearing fringes increased.At the same time,defects such as cracks and voids appeared,which was more likely to lead to debonding of the interface.