Joining of oxidation-resistant Mo–Si–B multiphase alloy to heat-resistant Mo–ZrC in-situ composite

Joining of oxidation-resistant Mo–Si–B multiphase alloy and to heat-resistant Mo–ZrC in-situ composite was studied through observation of microstructural evolution and measurement of hardness near the joint interface. As jointed at 1773 K for 7.2 ks, Mo3Si is formed in Mo–ZrC because of the non-equilibrium state between Mo and Mo5Si3. As jointed at 1973 K for 5.4 ks, a reactant containing Mo, Zr and Si is formed along the interface between Mo–Si–B and Mo–ZrC. Si is enriched in prior ZrC particles away from the interface in distances of 0 to about 4 μm. The hardness of Mo–ZrC after jointed at 1773 K shows no change near the joint interface in the range beyond 5 μm. On the other hand, the hardness values of Mo–ZrC jointed at 1973 K increases in the range of 0–10 μm. This indicates that Si diffuses at least by 10 μm into Mo in Mo–ZrC during bonding at 1973 K for 5.4 ks.