Research On Microstructure And Properties Of AlFeCrNiCoCu High-entropy Alloy Based Composites

Recently, high-entropy alloys was proposed by scholars of Taiwan. then the simple structure, Nano-Organizwtion and excellent performance of this alloy have been widely studied.This paper focuses on studying the microstructure and mechanical properties of Al_x(FeCrNiCo)Cu_y high-entropy alloys system in different Al, Cu composition. We also studied the influence of rare earth Y and reinforcement phase on the high-entropy alloys based composite materials.The experiments used vacuum arc melting furnace on the preparation of high-entropy alloys and its based composites, using optical microscopy, scanning electron microscopy, and other analysis methods to analyzed the microstructure of this materials. We also used the electronic universal mechanical testing machine, Hardness Tester, friction and wear testing machine to test the mechanical properties of high-entropy alloys and its based composite.After the study, we found in Al_x(FeCrNiCo)Cu_y high entropy alloy system, with the increase of Al element and the reduction of Cu elements, the crystal structure first consists of a simple system of fcc structure and then become disordered fcc + disordered bcc structure. Because of the increase of Al , Spinodal decomposition happens in the matrix. When x=0.75, y= 0.25,We can get the best properties, the fracture strength is up to 2787MPa, with extension rate 43.6%.This paper analyzed the influence of rare earth Y on the microstructure and properties of the matrix, the study found with the change of Y, great changes of material morphology take place.The tissue of spinodal decomposition changes into particles distributed in the disordered bcc structure. When x = 0.1, AlFeCrNiCo high-entropy alloy have the highest mechanical properties, its tensile strength and elongation are 2443MPa, 26.22%, compared to the matrix increase by 22.52%, 25.82%.Rare earth Y can also inhibites the growth of the reinforcement phase in the high-entropy alloy composites, and improves its wettability of the matrix ,so that the reinforcement phase partly become the nuclear core of the matrix and evenly distributes in the matrix. This eliminate segregation of the reinforcing phase in the grain boundary. Joining 0.1at.% of rare earth Y in the Al_0.75 (FeCrNiCo) Cu_0.25^-10%vol.TiC composite, the reinforcement particle size reduce by 50%, and much more evenly distributed in the grain,its yield strength as high as 1637MPa. Studies show that the strength and hardness of the high-entropy alloy composites increase as the increasing of volume of the reinforcement phase and comparing to the matrix wear-resistant increase more than 50%.