INTERFACE REACTIONS IN LIQUID-SINTERING TUNGSTEN HEAVY ALLOY WITH Si, Na IMPURITIES

SEM,TEM,XPS,and AES are used to analyze heavy alloys with different contents of trace impurities of Si and Na. The reactions caused by Si and Na at the interface of W-(Ni,Fe) and W-W and their effects on the microstructure of heavy alloy are also studied. It is found that the trace impurities of Si and Na result in the formation of pore and layer impurity phase of SiO₂ at the interface of W-(Ni, Fe). The low Wettability between SiO₂ and Ni,Fe and the volatility of Na during liquid phase sintering are the main reasons for such effect.