Unidirectional Solidifica Tion Of A Kind Of Nickel Base Single Cryst Alsuperalloy

In this paper, directional solidification was conducted on a new kind of nickelbase single crystal superalloy zone melted liquid metal cooling (ZMLMC). Effectsof growth rate on microstructure of a Ni-based superalloy were investigated. Thetemperature field for the simplified model of the unidirectional solidification issimulated by ANSYS, and the thermal gradient near the solid-liquid interface iscalculated then.The main conclusions of this paper are as follows:1. During the directional solidification of the superalloy, Al, Ta and Mo werepositive segregating elements, while W and Re are negative segregating elements.With the increase of the growth rate, the segregation ratio rised and then decline,but the tendency wasn't distinguished.2. With the increase of growth rate, the dendrite structure got refined, and both theprimary dendrite spacingλ1 and the secondary dendrite spacingλ2 reduced. Thesize ofγ' precipitates decreased, and the shape turned to be regular. In the samesample, theγ' phase in interdendrite area was larger and more irregular than that ofdendrite area. Theγ/γ' eutectics also became smaller and disperse with the increaseof growth rate, but the total volume fraction kept stable. 3. After the standard solution and aging process, the discrepancy in the dendritestructure and morphology ofγ' precipitates of the superalloy that resulted fromdifferent growth rates was entirely eliminated.