Characterization of fracture toughness and toughening mechanisms in Laves phase Cr₂Nb based alloys

The effect of Ti content on the fracture toughness of the Cr₂Nb-20/30/40Ti (in at.%) alloys has been investigated in the arc melting and heat treatment (1473K for 48h) conditions. The results show that the reduction of grain size and the facture toughness of the alloys increased with increasing the Ti content. After the heat treatment, the facture toughness of the Cr₂Nb-20/30Ti alloys increased by almost twice, and the crack bridging was primarily observed as the toughening mechanism, and for the Cr₂Nb-40Ti alloy, the fracture toughness increased by 77% and reached 18.80MPam^1/2, and the toughening mechanism transited to the crack defection. The alleviation of deformation constraint during the heat treatment was elucidated to be effective in improving the fracture toughness of the alloys.