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

Abstract

Directionally solidified NbSi₂/Nb₅Si₃ in-situ composites have been prepared. Scanning Electron Microscopes (SEM) and X-ray diffraction (XRD) have been used to investigate phase constitution and microstructure. It was found that microstructure and phase stability of directionally solidified alloys depended on growth rate, heat-treatment and alloying element. Compression strength was tested in the temperature range from 1473 to 1773 K and compression axes parallel to growth direction was chosen. High-temperature strength of NbSi₂/Nb₅Si₃ composites increased from 222.9 to 593.77 MPa at 1773 K due to Mo addition.