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

Fracture behavior and toughness of NbSi2-based single crystals and MoSi2(C11b)/NbSi2(C40) duplex crystals with a single set of lamellae

“…The C40-structured NbSi 2 has a wide solubility range with respect to Mo. The plastic deformation behavior is known to show significant differences, depending on the Mo content [6,7,17]. From this viewpoint, the compositional dependence of the fracture toughness was investigated using NbSi 2 , (Mo 0.50 Nb 0.50 )Si 2 and (Mo 0.85 Nb 0.15 )Si 2 single crystals.…”

“…C40-structured NbSi 2 is the most promising candidate for the reinforcing phase [4,5]. Also, NbSi 2 deforms even at low temperatures, and the yield stress shows anomalous strengthening at $1400°C [6][7][8]. In addition, C11 b -stabilizing elements such as Mo, W and Re effectively promote anomalous strengthening [7].…”

Plastic deformation behavior of NbSi2/MoSi2 crystals with oriented lamellae

“…MoSi 2 with the C11 b structure is known to be the most promising phase as a relatively more plastically deformable matrix than the other silicides because of possible operation of several slip systems even at low temperatures, but the high-temperature strength above 1200 C is not sufficient even after the addition of third elements [2e4]. In contrast, silicides with the C40 structure are expected to be potential materials for reinforcing the MoSi 2 matrix due to promotion of anomalous strengthening around 1500 C by addition of the C11 b -stabilized elements [5,6], although they show a limited slip system of ð0001Þ1=3 < 2110 due to the low crystal symmetry. Thus, NbSi 2 /MoSi 2 composites are expected to have a good balance of mechanical properties [7].…”

Effect of Mo Addition on Phase Stability and High-Temperature Strength of NbSi₂/Nb₅Si₃ Composites

“…NbSi 2 shows an anomalous strengthening peak in temperature range from 1673 to 1873 K, [10][11][12] which was reported to be due to the formation of the dragging atmosphere around the moving dislocation by interstitial and solute atoms. 10) These interstitial atoms are impurity in binary NbSi 2 , such as oxygen.…”

“…When the impurity atoms segregate around dislocation and form dragging atmosphere, an additional stress is required for the motion of dislocations to leave the atmosphere. Umakoshi 11) etc. reported that Mo atoms easily gather near the stacking fault between two 1=6h1 2 210i and form the dragging atmosphere.…”