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郑亮,刘玉峰,Gorley Michael J,Hong Zuliang,Day Sarah,Tang Chiu C,李周,张国庆.高温合金差示扫描量热分析(DSC)的影响因素研究II:粉末粒度和显微组织[J].稀有金属材料与工程(英文),2019,48(5):1591~1597.[Zheng Liang,Liu Yufeng,Gorley Michael J,Hong Zuliang,Day Sarah,Tang Chiu C,Li Zhou and Zhang Guoqing.Influencing Factors on Differential Scanning Calorimetry (DSC) Analysis of Superalloy II: Particle size and microstructure[J].Rare Metal Materials and Engineering,2019,48(5):1591~1597.]
Influencing Factors on Differential Scanning Calorimetry (DSC) Analysis of Superalloy II: Particle size and microstructure
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Received:October 19, 2018  Revised:November 21, 2018
DOI:
Key words: Ni-base superalloy  Alloy 625  DSC  synchrotron XRD  powder particle size  phase transformation
Foundation item:国家重点研发计划(2016YFB0701404);国家科技支撑计划(2015BAE03B01);国家自然科学基金(51304177);国家国际科技合作专项2012DFA50240;重点实验室基金(9140C430202150C43200);英国钻石同步辐射光源Diamond Light Source (EE10597)
Author NameAffiliation
Zheng Liang,Liu Yufeng,Gorley Michael J,Hong Zuliang,Day Sarah,Tang Chiu C,Li Zhou and Zhang Guoqing  
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Abstract:
      Differential scanning calorimeter (DSC) experiments were performed on a solid-solution strengthening Ni-base superalloy 625, considering the effects of the powder particle size (<37μm, 45-53μm, 75-105μm, 105-150μm, 150-355μm) and microstructure on the phase transformation temperature. The alloy powders were characterized by FESEM, EPMA and synchrotron XRD. The results indicate that the dendritic structure is evident in powders with different particle size and the dendritic arm spacing is in the 2-10μm range. Elements Ni and Cr are rich in dendritic core whereas the Mo and Nb tend to distribute in the interdendritic region. Only the matrix γ phase exists in the PM625 powders with different particle size range. The PM625 powders with weak segregation tendency exhibit a sharp inflection point in DSC heating curves in the region near solidus temperature, there is only a 2-5°C gap between the incipient melting temperature of the alloy (deviation from the baseline inflection point) and the nominal solidus temperature (tangent-onset intersection) for different particle size. However, the gaps between the norminal solidus and the end of the solidification temperatures are relative large, which is in 53-65℃ range, in DSC cooling curves, because the low segregation characteristic of original powders has been removed during the full remelting and re-solidified process. The differences in solidus, liquidus and incipient melting temperatures in DSC heating curves are maximum 3℃, 2℃ and 2℃ among different particle size powders, whereas they are 6℃ and 2℃ for the solidus and liquidus temperatures of the alloys in the cooling curves. Therefore, the particle size has minor effect on phase transformation temperature of solid-solution strengthening PM625 alloy powder.