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The NiSixbased alloy typically has poor weldability due toits lower ductility . Ali mited amount of workhas been performed on the weldability of NiSixbased alloys . Therefore ,the effect of heat treat ment and weldingparameters on weldability of the alloys ,and the relationship betweenthe weldability and microstructure were stud-ied . The results showthat the as-cast Ni-Si-Nb-Balloy (Ni 76·5 %,Si 20 %, Nb 3 %,and B0·5 %) could be suc-cessfully welded after preheating at 600 ℃. The welding procedure should be performed on the alloys before anyheat treat ment and a preheating at 600 ℃should be used . The fusion zone is harder than the matrix due to a largeamount ofγphase and a finer microstructure . The cracks are predominantlyintergranular in heat affected zone andassociated with the needle-likeγphase . The heat treat ment before welding increases the tendency of cracking inthe fusion zone .
The NiSixbased alloy typically has poor weldability due to lower lower utility. Therefore, the effect of heat treat ment and welding pararameters on weldability of the alloys, and the relationship betweehehe weldability and microstructure were stud-ied. The results show that the as-cast Ni-Si-Nb-Balloy (Ni 76.5%, Si 20%, Nb 3%, and B0.5%) could be suc- cessfully welded after preheating at 600 ° C The welding procedure should be performed on the alloys before any heat treatment and a preheating at 600 ° C should be used. The fusion zone is harder than the matrix due to a largeamount ofγphase and a finer microstructure. The cracks are predominantly intragranular in heat affected zone and heat-treatment before welding increases the tendency of cracking inthe fusion zone.