Correlation between tensile properties, microstructure, and processing routes of an Al-Cu-Mg-Ag-TiB2 (A205) alloy: Additive manufacturing and casting

This paper aims at assessing microstructure/processing route/mechanical property correlation of a high-strength TiB2/Al-Cu-Mg-Ag aluminum alloy, namely A205 alloy, additively manufactured via laser powder bed fusion (LPBF) versus the cast counter material. To this end, high magnification advanced microstructural characterization in connection with the tensile flow and strain hardening (i.e., work hardening) behavior of the materials were studied. Ambient temperature uniaxial tensile tests, based on ASTM E8/E8M, were conducted on the LPBF and cast as well as post-heat treated (T7: overaged and stabilized) materials were performed systematically. Results show a pronounced discontinuous yielding for the LPBF material along with extended ductility. The tensile curve of the LPBF T7 heat-treated material showed some plastic instabilities (Portevin-Le Chatelier effect) in the inelastic region. However, none of these phenomena were observed in the cast material, while ductility is limited. These responses were attributed to the very high cooling/solidification rates experienced by the LPBF materials, which result in a very fine equiaxed and supersaturated aluminum grain structure as compared with the coarse-grained structure of the cast counter material.