Structure and Distribution of Chemical Elements in the Transition Zone in Deposited VT20 and VT1-0 Alloy Samples

Abstract

Buildup (or additive manufacturing) processes enable the production of components where individual sections can possess distinct chemical compositions tailored to their specific purpose. However, the distribution of elements in the fusion zone and its sizes remain inadequately understood. Samples of VT1-0 and VT20 titanium alloys were fused so that the VT1-0 alloy powder was deposited onto the VT20 cast alloy in one case and the VT20 titanium alloy powder was deposited onto the VT1-0 cast alloy in the other. Regardless of the grain-size and chemical compositions of the powders, the chemical composition of the samples met relevant standards for the alloys. The macrostructures were studied employing a Neophot 32 optical microscope. Minimal porosity was revealed in the samples across all deposition options. Microstructural analysis showed that the deposited material formed a uniform structure both longitudinally and transversely. The microstructure in zones with specific chemical compositions resembled that of the associated as-cast alloys. Variations in the sizes and shapes of structural components were observed toward the powder/cast metal fusion line. A distinct transition zone was found in the fusion of titanium alloys with different chemical compositions. The chemical composition in the longitudinal and transverse sections in the powder/cast metal fusion zone was examined with a scanning electron microscope. The chemical composition was established at different distances from the fusion line. The results showed that the chemical elements redistributed and their contents changed. The presence of zones with altered chemical composition was ascertained by microstructural studies. The distribution of chemical elements was qualitatively assessed and found to be uniform.