Strengthening and toughening effects in laves phase Cr₂Ta/Cr in-situ composites by Si additions

Three Cr–8Ta-xSi (x = .0, 6, 10) (at.%) alloys were fabricated by vacuum non-consumable arc melting in this study to investigate the microstructure evolutions and mechanical properties of the Si-modified Cr₂Ta/Cr in-situ composites. The element Si was incorporated preferentially into Cr₂Ta rather than phase Cr, thus the microstructure transited from the dendrite Cr plus the eutectic Cr₂Ta/Cr in the Cr–8Ta alloy, to the full eutectic Cr₂Ta/Cr in the Cr–8Ta–6Si alloy, and finally to the dendrite Cr₂Ta plus the eutectic Cr₂Ta/Cr in the Cr–8Ta–10Si alloy. The Cr–8Ta–6Si alloy was developed with a good combination of strength and toughness, and the yield strength and fracture toughness of this alloy reached up to 960 ± 20 MPa and 15 ± 0.3 MPa m^1/2, respectively. The good combination of strength and toughness in the Cr–8Ta–6Si alloy resulted from the synergistic effects of solid solution strengthening, alloying toughening, interface strengthening and second phase toughening.