Phase Composition of D16 and V95 Deformable Aluminum Alloys with the Quantitative Assessment of Metal Burning at Various Stages of Development

Abstract

New methods to monitor metal burning in D16 and V95 aluminum alloys based on using energy-dispersive X-ray spectral analysis (EDS analysis) are shown. It is known that the reduced properties of aluminum-based materials are often associated with the presence of metal burning in the structure. The structural changes caused by metal burning (partial melting of eutectics and excessive low-melting phases with the subsequent crystallization of molten microvolumes) are often accompanied by the development of porosity and negatively affect the physicochemical, mechanical, and manufacturing properties. The ability to reveal metal burning at early stages makes it possible to reject the defective metal. The characteristics sensitive to the early metal-burning stage are proposed based on the EDS analysis. The induced metal-burning degree in a sheet of the D16 alloy is identified. The structural components of the V95 alloy determining the alloy liability to metal burning are established. It is shown that the EDS analysis makes it possible to reveal the variations in the chemical composition of structural elements of the D16 and V95 aluminum alloys, as well as quantitatively identify the metal-burning stage by the oxygen content. The metal-burning development leads not only to an increase in the oxygen content in the chemical composition of aluminum alloys, but also to a decrease in the electrical conductivity of the material. The correlation between the electrical conductivity of the D16 alloy with induced metal burning and oxygen content is considered. The applicability of the EDS analysis is due to the simplicity of the procedure and the possibility of quantitatively evaluating the development of defects in heat-strengthened deformed aluminum alloys after manufacturing heating. It can be used as an additional method for investigation when metallographic analysis gives an ambiguous answer when revealing early metal-burning stages.