Study on Mechanical Characteristics and Fracture Surface Morphology of the Ti-Surface-Modified AK5M2 Alloy

Abstract

The modification of metals and alloys by the external energy deposition methods makes it possible to locally strengthen the surface layer of parts and assemblies made of aluminum alloys. This study is aimed at revealing the regularities of the effect of electron beam processing modes on the mechanical characteristics and fracture surface morphology of the Ti-surface-modified AK5M2 alloy. The authors used the methods of modern physical materials science. The surface of the AK5M2 alloy was modified with a Ti film by the vacuum arc method. The modified samples of the AK5M2 alloy were irradiated with an intense pulsed electron beam in modes differing in the energy density of the electron beam (from 10 to 50 J/cm²). Mechanical tests were carried out by uniaxial tension to fracture of the alloy samples in the original state and the modified samples before and after the irradiation in five modes. Using scanning electron microscopy, the authors carried out a fractographic analysis of the fracture surface of the samples obtained as a result of tension. The development of a unique method for modifying the AK5M2 alloy makes it possible to improve its strength and morphological properties compared to the material in its original state. As a result of the mechanical tests, the authors determined the values of yield strength, ultimate tensile strength, and relative residual elongation and narrowing at fracture. The dependence between the change in the deformation characteristics and the structure of the fracture surface on the electron-beam processing modes was established. On the basis of the tests performed on the samples of the Ti-surface-modified AK5M2 alloy, the authors revealed a mode of electron-beam processing leading to the formation of a surface structure characterized by higher mechanical properties. The Ti surface modification of the AK5M2 alloy after electron-beam processing in a mode using an electron beam energy density of 30 J/cm² results in an increase in the strength characteristics. The parameters of this mode can be used for local hardening of parts made of this alloy, for example, bush bearings.