本文采用两种定向凝固工艺即功率下降(P.D)法和快速凝固(H.R.S)法研究了不同 Hf含量对一种镍签高温合金组织和性能的影响。实验结果表明，加入合金中的Hf主要偏析 在枝晶间和/'共晶相内；合金加Hf后，显微组织发生明显变化：/'共晶相大量增多，其形态也发生明显变化；晶界和枝晶间状态得到改善；出现了几种新的富Hf微量相。合金760℃持久性能（特别是横向性能）随Hf含量的増加显著提高。但1040℃的持久寿命却随Hf含量的 增加而下降。采用H.R.S工艺时合金的中、高温性能均明显优于P.D法工艺.文中讨论了合金加Hf后组织和性能变化的机理，确定了本合金较合适的含Hf量为1.0～2.0弗（重量），并认为应优先采用H.R.S定向工艺.

In this paper, the Influences of various Hf contents upon the microstructures and the mechanical properties of a Nickel-base superalloy by two different directionally solidified techniques(i.e. P.D process and H.R.S process)have been studied. The results show that Hf is always segregated along the interden-dritic regions and concentrated primarily in /' eutectic phases during sali-dification. The addition of Hf resulted in marked alteration of the microstructure of the alloy, i.e. the amount of /' eutectic phase increases obviously, and its morphology changes concurrently, the conditions of grain boundaries and interdendritic regions of the alloy are improved considerably, some minor Hf-rich phases, such as carbide MC(2), sulfurcarbide (M,Hf)2SC and Ni5Hf, were also observed. The stress-rupturs, properties, particularly the trensverse ones at 760℃ are enhanced with the increase of Hf content, however the stress-rupture life at 1040℃ decreased gradually with the increase of Hf content. The mechanical properties of the alloy prepared by H.R.S process at high and inter mediate temperature are considerably higher than those of the alloy prepared by P.D process. The mechanisms on the changes of microstructures and mechanical properties of the Hf-contained alloy were also discussed. The suitable range of Hf content in this alloy lies over 1.0～2.0% (by weight) and H.R.S technique should be adopted predominatingly,