Selection of the optimal composition of AlTiZrVNb coating using CALPHAD approaches

With the development of scientific and technological progress, the requirements for reliability (increased service life) of components and structural parts have changed. Machine components made from high‒carbon manganese steel are subject to wear, which can lead to increased costs. It is widely known that structures consisting of steel 76, GOST 51045‒97 are significantly wearing out. By modifying the surface layer using laser surfacing and subsequent melting, it becomes possible, through active mixing and rapid solidification that occurs during melting, not only to homogenize the structure, but also to implement hardening processes of the near‒surface layers of the most loaded (vulnerable) zones. Using the CALPHAD methods in the TermoCalc software package (software version number 2024.1.132110‒55), the effect of the applied protective coating (AlTiZrVNb) with subsequent melting on the change in the phase composition and distribution of elements on the outer crystalline layer of the substrate was simulated. An alloy of the composition Al31.17Ti18.55Zr1.56V27.53Nb21.19 was selected for the calculations. When laser radiation is applied to the deposited coating, active interaction of the coating components with the base metal (iron) is observed, resulting in the formation of a modified top layer containing new phases with iron in the composition. In this regard, using mathematical modeling, the Scheil method determined the crystallization rates and phases formed upon cooling in alloys located in the upper structure of the path after the reflow process: Al31.17Ti18.55Zr1.56V27.53Nb21.19, Al29.61Ti17.62Zr1.48V26.15Nb20.13Fe5.00, Al28.05Ti16.70Zr1.40V24.78Nb19.07Fe10.00, Al26.49Ti15.77Zr1.33V23.40Nb18.01Fe15.00, Al24.94Ti14.84Zr1.25V22.02Nb16.95Fe20.00, Al23.38Ti13.91Zr1.17V20.65Nb15.89Fe25.00, Al21.82Ti12.99Zr1.09V19.27Nb14.83Fe30.00, Al20.26Ti12.06Zr1.01V17.89Nb13.77Fe35.00, Al18.70Ti11.13Zr0.94V16.52Nb12.71Fe40.00, Al15.59Ti9.28Zr0.78V13.77Nb10.60Fe50.00, Al12.47Ti7.42Zr0.62V11.01Nb8.48Fe60.00. The crystallization process from 1600 to 500 °С of the obtained compositions is described using computational methods. When studying the solidification process, it was determined for all compositions that the iron content in the coating is about 10–25 at.% favorable for the formation of a good‒quality coating, since at these concentrations the material is in a single‒phase region.