Influence of nickel and germanium on the mechanical properties of aluminum alloys

Abstract

The aim Among non-ferrous alloys, aluminum alloys occupy an important position in the machine-building industry due to their high mechanical and service properties. In this paper, the microstructure and mechanical properties of an aluminum alloy were investigated during melting in an electric induction furnace, with varying amounts of germanium and nickel added. In the experiments, the aluminum alloy was melted up to 750 °C, and samples with different compositions were cast into sand–clay molds. Germanium was added to the charge in the form of GeO₂ in amounts ranging from 1 % to 3 % relative to the charge, while 2 % nickel powder was introduced into each sample. Mechanical property tests, including hardness and wear resistance, were carried out on the samples. The hardness of the specimens was measured using a THBRV-187.5DX hardness testing device. Hardness was measured on the HRA scale, and the addition of nickel increased the hardness of the aluminum samples. The highest hardness values were achieved when 2 % germanium and 2 % nickel were added relative to the charge. The wear resistance of the cast samples was determined using a special device equipped with a diamond disk. Wear resistance was evaluated based on the mass loss of the samples during testing. The diamond disk caused wear under a 5 N load applied to the specimens. In addition to mechanical property analysis, the samples' microstructure was also investigated. Microstructural studies revealed that the addition of germanium transformed the grain morphology from plate-like to more rounded. At the same time, a reduction in grain size was observed. Based on the analyses and experimental results, the paper presents valuable conclusions.