研究了5种不同含量的C对单晶高温合金凝固组织及持久性能的影响. 结果表明, 随着C含量的增加, 共晶数量明显减少, 碳化物数量增多, 且碳化物主要分布在枝晶间区域, 当C含量较高时, 在枝晶干上也有少量碳化物出现. 经过热处理后, 合金的枝晶间粗大的γ/γ′共晶基本消除, 枝晶间少量未被固溶掉的γ/γ′共晶, 达到了较好的均匀化效果; 碳化物形貌比铸态更为简单, 尺寸明显减小, 体积分数减小, 且分布更加弥散, 碳化物类型更加丰富, 出现了粒状和链状的M₂₃C₆碳化物. 随C含量增加合金的高温持久寿命先增大后减小, 当C含量为0.045%时, 高温持久寿命最大. 引起持久性能变化的主要原因是由于合金中未消除的共晶、碳化物及缩松的存在, 未消除的共晶以及碳化物都是裂纹萌生的位置, 而共晶和碳化物的数量随着C含量的增大又呈相反的变化趋势, 因此C的加入要适量.

The effects of carbon addition on the solidification microstructure and rupture life were investigated in five different carbon level single crystal superalloys. With the increasing of carbon level, the volume fraction of eutectic decreased markedly and the volume fraction of carbide increased. The carbides mainly distributed in interdendrite zone, when the carbon level was high, there were little carbides in the dendrite core. After heat treatment, coarse γ/γ′ eutectics in interdendrte zone mainly were dissolved, a little γ/γ′ eutectic was not dissolved. Morphologies of carbide became much simpler, the size of carbide decreased, the volume fraction of carbide decreased, and the distribution of carbide became much more dispersion, and the type of carbide became much more variety. Grain and chainlike M₂₃C₆ appeared after heat treatment. With the increasing of carbon level, the rupture life of single crystal superalloy increased at first and then decreased, and the rupture life came up to the maximum when the carbon level was 0.045%. SEM observation indicates that the cracks of alloys mainly originate from shrinkage, carbides and eutectics. The change of rupture life was mainly because the un-dissolved eutectic and carbides of alloy which act as the source of cracks. The variation trend of carbide and eutectic was contrary with the increasing of carbon level; therefore, the carbon content should be controlled in the perfect level.