The enhanced mechanical properties of laser powder bed fusion Al-Mn-Sc alloy via non-isothermal aging

Abstract

ABSTRACTThe post-heat treatment of laser powder bed fusion (LPBF) Sc-modified Al alloy is a remarkably necessary method to improve mechanical properties. In this work, the LPBF Al-Mn-Sc alloys with a high yield strength of 586 ± 4 MPa and excellent elongation of 14.5% were obtained by a novel and efficient non-isothermal aging (NIA) treatment at the heating rate of 2 °C/min from 30°C to 350°C. The precipitation behaviour and mechanical properties of the LPBF Al-Mn-Sc alloys after NIA treatment were investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM), hardness test as well as tensile test. The activation energy and Avrami exponent were calculated through DSC results with various heating rates. A non-isothermal aging kinetic model was applied to evaluate the NIA process referring to isothermal aging. The excellent mechanical property was analysed by revealing the strengthening mechanism of LPBF Al-Mn-Sc alloys after NIA.

Keywords

• Additive manufacturing
• Al-Mn-Sc alloy
• non-isothermal aging
• precipitation behaviour
• strengthening mechanism