微量Si在W－7Ni－3Fe重合金中的行为

研究了掺到原料Ｗ粉中微量Ｓｉ（４００ｐｐｍ）在Ｗ－７Ｎｉ－３Ｆｅ重合金中的分布及在液相烧结过程中的行为．结果表明，Ｓｉ主要以固溶形式分布在Ｗ晶粒中．Ｘ射线光电子能谱（ＸＰＳ）分析发现，在掺杂Ｓｉ的Ｗ－Ｗ及Ｗ－基体相界面富集ＳｉＯ２和Ｎａ２ＳｉＯ３在未掺杂试样的断口表面发现了较弱的ＷＯ２的ＸＰＳ谱，而在掺杂合金中未发现ＷＯ２．

BEHAVIOR OF TRACE Si iN W-7Ni-3Fe ALLOY

The distribution of trace Si (400 ppm), which was doped intentionally in raw tungsten powder, in W-7Ni-3Fe heavy alloy as well as the behavior of the impurities during the liquid phase sintering were investigated by scanning electron microscope and electron microprobe analysis. Trace Si was mainly distributed in the W grains as a solid solution in the sample prepared from the doped W powder. The X-ray photoelectron spectruscopy (XPS) analysis on the fracture surfaces of both doped and undoped samples showed that some SiO2 and Na2SiO3 were concentrated as SiO2 and Na2SiO3 in W-W and W-matrix interfaces of the doped sample. Weak XPS spectrum of WO2 was found on the fracture surface of the undoped sample but not found on that of the doped smple. The mechanism of the formation and elimination of WO2 thin film on the surfaces of tungsten grains was discussed from the point of view of the thermodynamic behavior of trace silicon during the liquid phase sintering of W-Ni-Fe heavy alloy.