Influence of silicide coatings on the mechanical properties of the NT-50 alloy

We have investigated the effect of silicide coatings on the ultimate strength of NT-50 alloy over the temperature range -196... +1100 deg C. From 196 to 800 deg the ultimate strength of silicidated specimens was lower than that of the initial and annealed alloy whereas from 900 deg C it was slightly higher. We have also examined the effect of silicide coatings on the relative elongation of NT-50 alloy samples. Over the temperature range -196...+1100 deg C, the relative elongation of specimens annealed in a vacuum of 6.7 x 10(-3) Pa at 1250 deg C for 4 h was found to be lower than that of the silicidated specimens. This is attributed to the dissolution of the residual gases (O2, N2, H2, CO, and CO2) under vacuum annealing.