Microstructural investigation of phase transformations and properties during thermal processing of a 6 w/oAl-modified Ni–Cr–Fe ternary alloy
Microstructural investigation of phase transformations and properties during thermal processing of a 6 w/oAl-modified Ni–Cr–Fe ternary alloy
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DOI：
10.1016/j.msea.2007.11.019
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发表时间：
2008-08
期刊：
影响因子：
6.4
通讯作者：
D. A. Akinlade;W. F. Caley;N. Richards;M. Chaturvedi
中科院分区：
文献类型：
--
作者：
D. A. Akinlade;W. F. Caley;N. Richards;M. Chaturvedi
采用差示扫描量热法研究了粉末冶金Inconel 600（Ni-Cr-Fe）基高温合金在添加6 w/o Al改性后，生坯从室温加热到1300°C烧结时的相变顺序、反应模式和产物。采用两种不同的加热速率进行DSC研究，2.5°C/min和10°C/min。还通过在DSC中将样品加热至放热/吸热点并在氩气中淬灭，然后通过X射线衍射进行相鉴定，并通过配备EDS功能的SEM进行微观结构分析来研究转化反应。在540°C至1120°C的温度下，观察到一系列AlxNiy和AlxFe型金属间化合物通过相变形成。这些相变形成金属间化合物的顺序与二元Ni-Al和Fe-Al平衡相图预测的金属间化合物形成顺序相似，最终组织为Ni-Cr-Fe（γ）基体中的Ni 3Al（γ′）、AlNi、AlFe。这些相变大多数是扩散控制的，然而在640°C下，AlNi通过燃烧合成形成。根据显微硬度估计合金在1120°C下对应于转变完成的选定机械性质，并与烧结态三元合金进行比较。
A differential scanning calorimetric study was carried out on a P/M processed Inconel 600 (Ni–Cr–Fe)-based superalloy modified by the addition of 6w/o Al to study sequence of phase transformations, their reaction modes and products on heating a green compact from room temperature to the sintering temperature of 1300°C. Two different heating rates were employed for the DSC study, 2.5°C/min and 10°C/min. Transformation reactions were also studied by heating the samples in a DSC to the points of exo/endothermicity and quenching in argon followed by phase identification by X-ray diffraction, and microstructural analysis by SEM equipped with EDS capability. A series of AlxNiy- and AlxFey-type intermetallics were observed to form by phase transformation at temperatures from 540°C to 1120°C. The sequence of the formation of intermetallics by those phase transformation closely replicated the intermetallics that were predicted by the binary Ni–Al and the Fe–Al equilibrium phase diagrams to form, with the final microstructure being Ni3Al (γ′), AlNi, AlFe in a Ni–Cr–Fe (γ) matrix. Most of these phase transformations were diffusion-controlled, however at 640°C AlNi formed by combustion synthesis. Selected mechanical property of the alloy at 1120°C which corresponds to the completion of transformation was estimated in terms of micro-hardness and compared to the as-sintered ternary.