STRENGTHENING AND TOUGHENING OF ALUMINUM ALLOYS

Abstract

The paper focuses on the problem of traditional strengthening of aluminum alloys, such as the solid solution strengthening, second phase strengthening, grain refinement strengthening, and mechanical hardening. Composite reinforcement is the use of high-strength powder, wire, and sheet materials to undergo pressure, welding, spraying and solution dipping methods with the aluminum matrix composite, so that the matrix could obtain high strength. This article reveals the four traditional strengthening mechanisms of aluminum alloys, briefly introduces the mechanism of composite strengthening, and compares several strengthening modes. According to the shape of the composite material, composite reinforcement can be divided into fiber, particle and material wrapping one. Most of the traditional strengthening methods are to improve the strength of aluminum alloys by sacrificing plasticity and adding defects (mainly dislocations) in the crystal to impede the dislocation movement. This paper also briefly introduces the process of composite strengthening, which is different from the traditional strengthening methods which enhance the material characteristics by obstructing the movement of dislocations. The composite strengthening relies on good infiltration between the fiber and the matrix for a tight joint, so that the fiber and the matrix can obtain a good bond strength. Most of the traditional strengthening mechanisms increase the strength of the alloy at the expense of plasticity, which restricts the development of the comprehensive aspects of aluminum alloys. At present, the main methods of aluminum alloy strengthening are grain refinement and second phase strengthening. In particular, the second phase strengthening has a significant effect on the performance improvement of aluminum alloys. In the future development of aluminum alloys, it is not only necessary to improve the strength, but also to make comprehensive performance in all aspects better. Composite strengthening involves the advantages of each component, making up for their own drawbacks, and has a good development prospect.