DZ125定向凝固镍基高温合金组织与熔体超温处理时间的相关性

Relationship between Microstructure and Melt Superheating Time for Directionally Solidified DZ125 Superalloys

采用熔体超温处理方法,通过改变熔体超温处理时间研究定向凝固镍基高温合金DZ125凝固组织的演化规律。结果表明:熔体超温处理时间由15min延长到30min可以细化枝晶、减小偏析。然而,进一步延长熔体超温处理时间至60min,枝晶却略微粗化。熔体超温处理15min时,碳化物形貌为草书体,而熔体超温处理时间大于30min时碳化物则主要为非连续性棒状和块状。造成这种现象的主要原因是熔体超温处理时间的变化影响到熔体状态,进而影响到凝固组织。

The solidification microstructure evolution of Ni-based superalloy DZ125 with melt superheating time was investigated.The results show that the dendrite arms are evidently refined and the segregation is reduced with the increase of melt superheating time when the melt superheating time is less than 30 min.However,further prolonging melt superheating time,the dendrite arms become coarser lightly.The morphology of carbide presents from script-like to blocky and nodule when the melt superheating time increases from 15 to 30 min.But when melt superheating treatment time is prolonged to 60 min,the morphology of carbide is still mainly blocky and nodule.The reason of solidification microstructure evolution is the change of melt structure with the prolonging of melt superheating time.