Поверхностное упрочнение алюминиевых сплавов химическим никелированием

Abstract

The hardening of aluminum AK4 (2618, ANSI H35.2) and B95(AA7075, ANSI H35.2) alloys was carried out by the method of chemical nickel plating. The distribution of mi-crohardness over the coating section was studied. The hard-ness of the hardened AA7075 alloy alloy was 1.9 times higher than for hard-ened 2618 alloy. It has been shown that parameters of the nickel coating (thickness, microhardness, phase composition) depend on the chemical composition of the processed aluminum alloy. When processing the AA7075 alloy, the maximum values of coating thickness and microhardness were observed. It was found that during the thermal treatment of chemically nickel-plated AA7075 alloy, the formation of an AlNi inter-metallide at the coating boundary and base. It has been shown that the maximum microhardness is achieved in the lower part of the coating, which is 40-50% of its thickness. As it approaches the interface between the coat-ing and treated material, the microhardness increases mono-tonically to a maximum, and then decreases monotonically to the microhardness corresponding to the base material. On the diffractogram of aluminum AA7075 alloy sample after ther-mal treatment it is observed appearance of AlNi intermetal-lide in the main peak. On the diffractogram of the aluminum 2618 alloy sample after thermal treatment Al-Ni solid solu-tion is observed only. The formation of a nickel coating with such distribution of micro-hardness values on the aluminum AA7075 alloy will allow the hardened product to be "worked in" during opera-tion. It should favorably influence on the work resource of the product as a whole.