The dense Ni 3 Al with different boron and chromium addition was fabricated by the thermal explosion and hot extrusion (TE/HE) technology. Microstructure examination showed that Ni 3 Al contained fine grain structure (200nm to 10μm). Analysis of X-ray spectra as well as transmission electron microscopy studies revealed that three phases present in all alloys: γ-Ni, Ni 3 Al and dispersoids of Al 2 O 3 . With the addition of B, β-NiAl phase and twinned Ni 3 Al formed, but in the B and Cr doped alloy, Cr rich phase and a spot of Cr 7 Ni 3 particles with stacking faults inside were observed. In addition, dislocations with high density existed in all alloys. The mechanical test showed that the B and Cr addition resulted in significant improvement in mechanical properties, and TE/HE synthesized Ni 3 Al alloy owned more excellent mechanical properties, compared with the one synthesized by combustion.