【摘要】 高铝钛铸造镍基高温合金的凝固与偏析是极复杂的过程,本文测定了凝固过程中各种相的形成顺序、成分变化及合金元素的分配系数等,着重讨论了(γ+γ′)共晶的形成过程和控制该合金析出σ相的办法。更多还原

【Abstract】 An investigation was made of the various phases formed in what order and composed under different temperatures during the process of solidification and segregation of alloying elements in a high Al-Ti cast Ni-base superalloy. The formarion of (γ+γ’) eutectic and the control of σ-phase precipitation have been discussed. During solidification of the alloy, the dendritic segregation of Al and V is almost unespied, and of Ti, Cr and Mo is positive, especially, Ti being the most serious. This may impel the formation of segregation zone at eutectic reaction and the enrichment with σ- phase forming elements, e.g. Cr, Mo and Co, in the remainder liquid. Thus the increasing of σ-phase transformation may be tended. However, the σ-phase may be avoided either by adjusting the ratio Al/Ti taking the advantage of the difference of the segregation behaviour of Al and Ti, or by controlling the cooling rate after casting.更多还原