Effect of Ternary Alloying Elements on Microstructure and Mecanical Property of Nb-Si Based Refractory Intermetallic Alloy

초록

Microstructure and mexhanical property at room temperature and at 1773K of Nb-Si based refratory intermetallic alloys were investigated in terms of compression and fracture toughness test. Mo and V were choen as ternary alloying elements because of their high melting points, atomic sizes smaller than Nb. Both ternary alloying elements were found to havea significant role in modifying the microstructure from dispersed structure to eutectic-like structure in Nb solid solution/Nb5Si3 intermetallic composites. The 0.2% offset yield strength at room temperature increased with increasing content of ternary elements in Nb solid solution and volume fraction of Nb5Si3. At 1773K, Mo addtion has a positive role in increasing the yield strength. On the other hand, V addition has a role in decreasing the yield strngth. The fracture toughness of ternary alloys was superior to binary alloys. Details will be discussed in correlation with ternary alloying. Volume fraction of constituent phase, and the microstructure.