Investigation of the Influence of Alloying Elements Ni, Cr, Co and Mo on the Crystallization Process, Phase Composition and Corrosion Resistance of AlSi25Cu4Cr and AlSi25Cu5Cr Alloys

To increase the mechanical and improve the operational properties of the AlSi25Cu4Cr and AlSi25Cu5Cr alloys, combinations of the alloying elements Ni, Co and Mo were used. The AlSi25Cu4Cr alloy was additionally alloyed with both Ni and Mo and Ni, Co and Mo, and the AlSi25Cu5Cr alloy was alloyed with Co and Mo in different concentrations. The dental alloys “wiron light” and “wironit” were used to introduce the elements Ni, Co, Mo, as well as additional amounts of Cr into the composition of the base compositions. The thermal analysis recorded a decrease in the liquidus and solidus temperatures of the base alloys, as well as a narrowing of their crystallization temperature range as a result of the added alloying elements. The influence of the used chemical elements on the phase composition of the alloys was established by X-ray diffraction. The elements Cr and Mo do not form secondary strengthening phases but dissolve in the α-solid solution. The results of the corrosion tests conducted in 1 M HCl solution and 1 M H2SO4 solution for 336 h and 504 h show that the elements Ni, Co and Mo improve the corrosion resistance of the alloys.