Heterogeneous deformation-induced strengthening of extruded Tip/WE43 composites

Abstract

Titanium (Ti) particles reinforced WE43 (Mg-4Y-2Nd-1Gd-0.5Zr) matrix composites (Tip/WE43) were prepared via ultrasonic-assisted stirring casting and following hot extrusion. Ti particles can refine the grains and promote the precipitation of the second phases in magnesium (Mg) matrix. Meanwhile, bimodal structures combining coarse deformed grains and recrystallization equiaxed grains were formed. The generation of heterogeneous interfaces promotes heterogeneous deformation-induced (HDI) strengthening. Extruded 3Tip/WE43 with a yield strength (YS) of 241 MPa, an ultimate tensile strength (UTS) of 283 MPa, and an elongation (EL) of 17.3%, respectively, possesses an excellent strength–ductility combination. The interfacial product of Ti/Mg was mainly composed Ti3Al layer with about 200 nm, which was conducive to interfacial bonding and stress transfer. The dislocation entanglements and stacking faults inside the Ti particles can promote the coordinated deformation between the Mg matrix and Ti particles. The rare-earth rich phases Ti2ZrAl, Mg41Nd5, and Mg24Y5 precipitated in the matrix can hinder dislocation movement by activating Orowan strengthening. The key factors of YS increment of the composites were considered to be HDI strengthening, fine grain strengthening, and thermal mismatch strengthening.