烧结过程中Co粉和Ni粉扩散溶解的研究

Diffusion and Dissolution of Co Powder and Ni Powder During Sintering

利用光学显微镜、扫描电镜、X射线衍射和能谱技术研究了Co粉和Ni粉固相烧结时形成的烧结体的微观形貌和相结构;并利用原子相图讨论了Co-Ni固溶体的形成机理、计算了该固溶体的电子密度。结果表明,不同混合比例的Co粉和Ni粉压坯在1000℃×36 h的烧结过程中,Co原子以间隙扩散机制进入Ni粉末颗粒,而Ni原子几乎不能进入Co粉末颗粒,最终全部形成Co-Ni无限间隙固溶体,同时使固溶体晶界处产生大量孔隙,该固溶体的电子密度为3.2709×1029个/m3。

The microstructure of sinter of Co powder and Ni powder formed during sintering was studied by OM, SEM, EDS and X-ray diffraction. The formation mechanism of Co-Ni solid solution was discussed and electron density of Co-Ni solid solution was calculated by means of Thomas-Fermi-Dirac-Cheng phase diagram（TFDC）. The results show that the various mixtures of Co and Ni entirely come into being Co-Ni infinite interstitial solid solution, a great deal of holes produce at grain boundary of solid solution because only Co atoms can diffuse into Ni powder granules and Ni atoms hardly diffuse into Co powder granules during sintering at 1 000 ℃ for 36 h. The electron density of Co-Ni solid solution is 3.2709 × 10^29/m^3.