Effect of annealing environment on the crack healing and mechanical properties of (Mo0.97Nb0.03)(Si0.97Al0.03)2

• (Mo0.97Nb0.03)(Si0.97Al0.03)2 is prepared by a cost-effective and less energy process.
• Notched samples show significant recovery of bending strength after annealing in air.
• The bending strength recovery is 208% in vacuum, 149% in Ar and 153% in N2.
• Re-sintering is the dominant mechanism of crack healing in non-oxidizing conditions.

Crack healing of Nb and Al alloyed MoSi2 notched ceramics had been investigated during thermal treatment from 900 to 1500 °C in air, vacuum, argon and nitrogen environments. Notched (Mo0.97Nb0.03)(Si0.97Al0.03)2 ceramics showed significant recovery of bending strength after heat treatment in air. Bending strength recovery of 250% was found after heat treatment in air at 1200 °C. Oxide layer formation healed the cracks during annealing in air. Re-sintering was found dominant mechanism of crack healing during annealing in vacuum, argon and nitrogen atmosphere. Bending strength recovery of 208% was found after heat treatment in vacuum at 1200 °C.