Effect of alloying elements on anomalous strengthening of NbSi2-based silicides with C40 structure

Plastic behavior of binary and NbSi2-based ternary disilicides containing Mo and W with the C40 structure was investigated at temperatures between 20 and 1700°C using single crystals. The binary and ternary disilicides were deformed only by the (0001)〈12̄10〉-slip at all tested temperatures. They showed anomalous strengthening at high temperatures. Addition of Mo and W was effective in the anomalous strengthening and shifted the anomalous peak to around 1600°C. The peak height increased with increasing Mo and W concentration. The anomalous strengthening is closely related to the formation of dragging atmosphere around moving dislocations. The effect of additional elements on the dragging atmosphere is discussed on the basis of the phase stability between analogous crystal structures of C11b and C40.