A microcompression study on the mechanical properties and fracture behavior of Be–Al and Be–AlSi10Mg alloys fabricated by laser solid forming

Abstract

The microstructure and micropillar compression responses of thin-walled Be–Al and Be–AlSi10Mg samples, produced by laser solid forming (LSF), were investigated. Both alloys resembled typical 3-D net-shaped structures. The Be–AlSi10Mg alloy exhibited coarser Be grains embedded in the refined Al net-like matrix owing to a broader solidification region. Owing to the multi-hardening by Si and Mg alloying, the yield strength of the system significantly increased from 150 MPa to 220 MPa. In addition, the failure mode changed from plastic fracture of the Al phase in Be–Al to brittle fracture of the Be phase in Be–AlSi10Mg during microcompression. Based on the theoretical calculation of the yield strength and fracture strength, grain size refinement by the non-uniform nucleation process was dominant factor affecting the Al matrix strength increment of Be–AlSi10Mg. Meanwhile, the critical resolved shear stress of Be was smaller than the ultimate strength of the Al phase strengthened by Si and Mg in the Be–AlSi10Mg alloy. Thus, the failure preferentially occurred in the Be phase rather than the Al phase. These results suggest that improving the fracture strength of the Be phase is important for obtaining high-performance Be–Al alloys after the strengthening of the Al phase by alloying additions and artificial aging measurements.