冷坩埚定向凝固工艺参数对Ti-46Al-0．5Si-0．5W合金扁锭宏观组织的影响

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A composition of Ti-46Al-0.5Si-0. 5W was prepared with directional and fine grains in slab shape. The effects of technical parameters on the grain modalities are studied with orthogonal experiments. The results show that with increasing power grains trends to grow up while the direction of grains is improved. Grains trend to be finer but the direction is more deviated from the growth direction in some extension with increasing withdrawal velocity. When the preheating time is prolonged, the size and the direction of grains both trend to be disbennifit. All of the best directional structures arc obtained with withdrawal velocity 1.0mm/min for different crucibles and compositions.利用冷坩埚定向凝固技术制备了晶粒较为细小柱状晶的Ti-46Al-0．5Si-0．5W扁锭试样。采用正交试验法考察了工艺参数对凝固组织晶粒形态的影响趋势。结果表明，随着功率增大，晶粒长大倾向明显，但晶粒的生长方向性会改善；随着抽拉速度增大，晶粒尺寸变小，但方向性会在试样一定范围内变差；随着预热时间延长，晶粒尺寸和取向均有变差的趋势。在抽拉速度为1．0mm／min时获得了最佳的定向凝固组织。