微量元素对镍基高温合金共晶数量的影响

摘要

利用光学显微镜、扫描电子显微镜、定量金相分析、差示扫描量热仪等研究了微量元素对一种镍基高温合金共晶数量的影响.结果表明,添加B、Zr、Y等元素都使合金的共晶数量有了明显的增加,而且同时加入两种微量元素对共晶数量的影响更加显著.分析表明,Zr、Y等元素由于具有较大的原子半径,阻碍了元素的扩散,导致糊状区偏析加剧而促进共晶组织的形成.而添加B增大了凝固区间,从而促进元素偏析导致共晶数量增加.%Optical microscope, scanning electron microscope, quantitative metallographical analysis and differential scanning calorimeter were employed to study the influence of trace elements on the volume of eutectic colonies in a Ni-based superalloy. The results show that the additions of B, Zr and Y increase the eutectic volume remarkably, and the influence is more astonishing if two trace elements were added simultaneously. It is proposed that Zr and Y have large atomic radii, which retard the diffusion of other elements, thereby aggravate the segregation of the mushy section during the final stage of solidification. As a result, the eutectic volume increases. While the addition of B enlarges the solidification range of the alloy, thereby promotes the segregation of alloying elements, which leads to the increment of eutectic.