Mechanical behavior at elevated temperatures of an Al–Mn–Mg–Sc–Zr alloy manufactured by selective laser melting

Abstract

A high temperature compression and compression creep study was undertaken performed on Al–Mn–Mg–Sc–Zr alloy produced by selective laser melting (SLM). High temperature compression tests in the temperature range from 150 to 300 °C were conducted for the as-fabricated (AF) and aged (HT) SLM specimens. The 0.2% proof stress (σ0.2) showed comparable values at different loading directions, which reveal an isotropic mechanical behavior. σ0.2 of the HT samples exceeded that of the AF at temperatures up to 200 °C. At 250 °C, σ0.2 of AF surpasses that of HT, due to the interaction of solid solution strengthening above 0.5 of the homologous temperature and the formation of new precipitates in this temperature range. For AF and HT σ0.2 becomes similar again at 300 °C. Creep tests were conducted at 250 °C in a stress range of 100–150 MPa. The Norton stress exponent was determined to (5.1 ± 0.2) indicating that creep is dislocation climb controlled. An activation energy for creep of (198 ± 11) kJ/mol was found. It is suggested that solid solution strengthening in conjunction with a dispersed L12 Al3Sc precipitates improved the creep resistance compared to conventionally cast-manufactured Al–Sc–Zr alloys.