Microstructure evolution and tensile behavior of MgAlB4w/Al composites at high temperatures.

• High temperature mechanical behavior of MgAlB 4 w/Al was studied. • UTS of 20 wt% MgAlB 4 w/Al composite at 300 °C can reach up to 166 MPa. • The failure behavior changes from the whisker fracture to interfacial debonding. High temperature tensile properties and fracture mechanism of the MgAlB 4 w/Al composites. [Display omitted] Aiming at developing high temperature resistance aluminum matrix composites for both structural and functional purposes, the novel MgAlB 4 whisker reinforced Al matrix composites with directional distributed reinforcement were fabricated using powder metallurgy followed by hot extrusion. The microstructure characterization demonstrated that Al grains exhibited a distinct< 111 > Al texture and MgAlB 4 whiskers aligned along the extrusion direction in the as-extruded composites. The high temperature tests indicate that UTS of the 20 wt% MgAlB 4w /Al composite at 200 °C and 300 °C can reach up to 266 MPa and 166 MPa, respectively, with a CTE of 23.7 × 10−6 K−1 at 300 °C. The whiskers distributed within the grains have a pinning effect on the dislocation movement and the whiskers distributed on the grain boundaries impede the grain boundaries sliding and migration. Additionally, the failure behavior changes from MgAlB 4 whiskers fracture to interfacial debonding of MgAlB 4w -Al matrix as the temperature increases. [ABSTRACT FROM AUTHOR]