熔体处理对DD426单晶高温合金凝固组织的影响OACSTPCD

The first generation single crystal superalloy DD426 was prepared by different melt treatment processes.The solidification path and solidification characteristic temperature of the alloy were determined by combining differential thermal analysis and JMatPro simulation calculation.The micro structure of the samples prepared by different processes was observed by scanning electron microscopy,and the micro-pores in the samples were characterized by three-dimensional X-ray computed tomography.The results showed that with the increase of melt treatment temperature,the crystallization temperature decreased firstly and then increased,leading to the change of primary/secondary dendrite arm spacing.The morphology of carbides mainly depended on the alloy composition(carbon element and carbide forming element)and solidification conditions(growth space and time).The size,quantity and distribution of micro-pores in the alloy were affected by dendrite spacing,carbide content and morphology.