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以国内第2代单晶高温合金DD6为研究对象,研究了型壳中央散热对其凝固组织与持久性能的影响。结果表明,与合金中柱型壳相比,石墨中柱型壳能有效地改善单晶凝固过程中温度场的均匀性,提高温度梯度,有利于保持单晶凝固过程中热流方向的平直。因此,石墨中柱型壳有利于降低一次枝晶间距,细化γ-γ′共晶相,减少单晶生长方向与[001]方向的角度差,使单晶高温合金获得较高的持久寿命。
Taking the second generation single crystal superalloy DD6 as the research object, the influence of central cooling of the shell on its solidified structure and ductility was studied. The results show that compared with the middle cylinder shell, the graphite middle cylinder shell can effectively improve the uniformity of the temperature field during the single crystal solidification and increase the temperature gradient, which is beneficial to maintain the straightness of the heat flow in the single crystal solidification. Therefore, the graphite cylindrical shell helps to reduce the primary dendrite spacing, refine the γ-γ ’eutectic phase and reduce the angle difference between the growth direction of the single crystal and the [001] direction, so that the single-crystal superalloy has higher long-life .