Development and characterization of a metastable Al-Mn-Ce alloy produced by laser powder bed fusion

Abstract

• Al 92 Mn 6 Ce 2 alloy was processed crack-free by laser powder bed fusion (LPBF). • The high cooling rate leads to a high amount and a strong refinement of metastable Al 20 Mn 2 Ce. • The compressive behavior overcomes as-cast Al 92 Mn 6 Ce 2 and many conventional Al alloys. Laser powder bed fusion (LPBF) can help to overcome two challenges occurring by casting of metastable Al alloys: (1) the high amount of casting defects and (2) the limited part size while maintaining rapid solidification of the whole cross-section. In this study, an Al 92 Mn 6 Ce 2 alloy was processed crack-free without baseplate heating by LPBF. The high cooling rate during fabrication has a significant impact on the microstructure, which was characterized by SEM, TEM and XRD. The processing through LPBF causes a high amount and a strong refinement of the intermetallic Al 20 Mn 2 Ce precipitates. This leads, compared to suction-cast specimens, to a higher hardness (180 HV 5) and a higher tolerable compressive stress (>1200 MPa) associated with a pronounced plasticity without failure up to a strain of 40%. The extraordinary mechanical properties of additively manufactured Al 92 Mn 6 Ce 2 can extend the possibilities of producing novel LPBF lightweight structures for potential applications under harsh conditions.