Microstructure and mechanical properties of Ni3Al and Ni3Al–1B alloys fabricated by SHS/HE

The well-densified Ni3Al alloys without and with boron addition were fabricated by self-propagation high-temperature synthesis and hot extrusion (SHS/HE) technology. Microstructure investigation showed that Ni3Al and Ni3Al-1B alloys contained fine grain structure. Analysis of X-ray spectra as well as transmission electron microscopy studies revealed that three phases present in all alloys: γ-Ni, Ni3Al and dispersoids of α- Al2O3 and γ- Al2O3. However, β-NiAl, Ni3B phase and twinned Ni3Al crystal are observed in the Ni3Al-1B alloy. In addition, dislocations with high density exist in all alloys. The mechanical test showed that the B addition leads to obvious improvement in yield strength and compressive ductility, and compared with the ones synthesized by combustion, SHS/HE synthesized Ni3Al and Ni3Al-1B alloys exhibit more excellent mechanical properties.