EFFECT OF AlTi3B1 INOCULANT ON THE MICROSTRUCTURE AND HARDNESS OF THE AlCu4Mg1 ALLOY

Abstract

Aluminum alloy EN AW-2024 (AlCu4Mg1 - dural) – Al-Cu-Mg group is one of the most used alloys from this group, which achieves considerable strength after heat treatment. It is an alloy with higher and high strength, but low corrosion resistance. The mechanical properties of Al-Cu alloys depend on whether Cu is present in the aluminum solid solution α in the form of a spheroid, possibly as dispersed particles or if it is forming a network at grain boundaries. The paper is focused on the evaluation (microstructure, grain size, phase fraction, hardness) of this particular alloy using AlTi5B1 inoculant in various concentrations to refine the alloy grain. The heat treatment of the alloy was also performed in the experiment to increase the mechanical properties. Inoculation of aluminum alloys is performed to improve the mechanical and technological properties of the material. In the case of inoculation, this improvement is mainly due to an increase in chemical and structural homogeneity and a decrease in the tendency to segregate individual elements. Optical microscopy and image phase analysis was used to observe the microstructure, which evaluated the microstructure and its changes depending on the content of the inoculant and also the effect of heat treatment in the combination of different amount of inoculant. It is generally known that AlTi5B1 acts in certain amounts to refining the alloy grain. Our work is based on the knowledge of the behaviour of different concentrations of inoculant in this particular AlCu4Mg1 alloy and responds to the requirement from practice. We achieved the best results with a concentration 3 wt% of AlTi5B1. For the other concentrations, the results were almost comparable and not much worse than for the concentration with the best results. It doesn't make sense to add more than 3 wt% of inoculant in this case.