A vectorization analysis technique for crystal growth and microstructure development in single-crystal weld was developed in our previous work. Based on the vectorization method, crystal growth and stray grain distrib...A vectorization analysis technique for crystal growth and microstructure development in single-crystal weld was developed in our previous work. Based on the vectorization method, crystal growth and stray grain distribution in laser surface remelting of single crystal superalloy CMSX-4 were investigated in com- bination of simulations with experimental observations. The energy distribution of laser was taken into consideration in this research. The experimental results demonstrate that the simulation model applies well in the prediction of dendrite growth direction. Moreover, the prediction of stray grain distribution works well except for the region of dendrites growing along the [100] direction.展开更多
The Cu65Ni35,Cu60Ni40 and Cu55Ni45 alloys were undercooled by fluxing method,and the rapid solidification structure with different undercoolings were also obtained.At the same time,the interface migration process duri...The Cu65Ni35,Cu60Ni40 and Cu55Ni45 alloys were undercooled by fluxing method,and the rapid solidification structure with different undercoolings were also obtained.At the same time,the interface migration process during rapid solidification was photographed by high-speed photography,and the relationship between the morphological characteristics of solidification front and undercooling was analyzed.The microstructures of the three alloys were observed by metallographic microscope,and the microstructure characteristics and evolution law were systematically studied.It was found that two grain refinement events occurred in the low undercooling range and high undercooling range,respectively.The EBSD test of grain refined microstructures showed that the microstructure in the low undercooling range has a high proportion of low-angle grain boundaries and high strength textures.However,there were a large proportion of high-angle grain boundaries and a high proportion of twin grain boundaries and more randomly oriented grains in the microstructure in the high undercooling range.The TEM test of the Cu55Ni45 alloy with the maximum undercooling of 284 K showed that there were high-density dislocation networks and stacking faults in the grains.Finally,the evolution relationship between microstructure hardness and undercooling was systematically studied.It was found that the microhardness of the three alloys decreased sharply near the critical undercooling.Combined with EBSD,TEM and microhardness analysis,it was confirmed that the grain refinement under low undercooling was caused by dendrite remelting,while the grain refinement under high undercooling was caused by stress-induced recrystallization.展开更多
基金financially supported by the National Natural Science Foundation of China (NSFC) under grant Nos. 51401210 and 51271186the National High Technology Research and Development Program (863 Program) of China under grant No. 2014AA041701
文摘A vectorization analysis technique for crystal growth and microstructure development in single-crystal weld was developed in our previous work. Based on the vectorization method, crystal growth and stray grain distribution in laser surface remelting of single crystal superalloy CMSX-4 were investigated in com- bination of simulations with experimental observations. The energy distribution of laser was taken into consideration in this research. The experimental results demonstrate that the simulation model applies well in the prediction of dendrite growth direction. Moreover, the prediction of stray grain distribution works well except for the region of dendrites growing along the [100] direction.
文摘The Cu65Ni35,Cu60Ni40 and Cu55Ni45 alloys were undercooled by fluxing method,and the rapid solidification structure with different undercoolings were also obtained.At the same time,the interface migration process during rapid solidification was photographed by high-speed photography,and the relationship between the morphological characteristics of solidification front and undercooling was analyzed.The microstructures of the three alloys were observed by metallographic microscope,and the microstructure characteristics and evolution law were systematically studied.It was found that two grain refinement events occurred in the low undercooling range and high undercooling range,respectively.The EBSD test of grain refined microstructures showed that the microstructure in the low undercooling range has a high proportion of low-angle grain boundaries and high strength textures.However,there were a large proportion of high-angle grain boundaries and a high proportion of twin grain boundaries and more randomly oriented grains in the microstructure in the high undercooling range.The TEM test of the Cu55Ni45 alloy with the maximum undercooling of 284 K showed that there were high-density dislocation networks and stacking faults in the grains.Finally,the evolution relationship between microstructure hardness and undercooling was systematically studied.It was found that the microhardness of the three alloys decreased sharply near the critical undercooling.Combined with EBSD,TEM and microhardness analysis,it was confirmed that the grain refinement under low undercooling was caused by dendrite remelting,while the grain refinement under high undercooling was caused by stress-induced recrystallization.
