Modification of composition, structure and mechanical properties of the surface layer of (Ti, Cu)N/Al – 12 at. % Si alloy system treated by compression plasma flows

Abstract

Changes in composition, structure and properties of the surface layer of (Ti, Cu)N/Al – 12 at. % Si alloy treated by compression plasma flows were investigated. Scanning electron microscopy, energy dispersive analysis, X-ray diffraction, microhardness and friction coefficient measurements were used as investigation techniques. Increase of the energy density absorbed by the samples surface in the region of 26 – 40 J/cm2 during plasma impact leads to the growth of coating material dissolution degree in the surface layer of aluminum alloy and diminishing of titanium and copper content in it. Decrease of alloying elements concentration is explained by the growth of melted layer thickness and erosion intensity during plasma impact. The formation of a surface homogeneous layer with dispersed structure and thickness of 25– 45 µm, consisting of substrate and coating elements was observed in the region of the absorbed energy density 35– 40 J/cm2. A supersaturated solid solution based on aluminum is formed, as well as a surface film of aluminum nitride. Plasma impact leads to an increase in the microhardness of the surface up to 25 % compared to the initial alloy. A sample processed at an absorbed energy density of 30 J/cm2 has the lowest friction coefficient.