Comparison of Chromia Growth Kinetics in a Ni-based Superalloy, with and without Shot-peening
Comparison of Chromia Growth Kinetics in a Ni-based Superalloy, with and without Shot-peening
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DOI：
10.1016/j.corsci.2015.07.033
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发表时间：
2015-11
影响因子：
8.3
通讯作者：
S. Cruchley;M. P. Taylor;R. Ding;H. Evans;D. J. Child;M. Hardy
中科院分区：
文献类型：
--
作者：
S. Cruchley;M. P. Taylor;R. Ding;H. Evans;D. J. Child;M. Hardy
本文研究了喷丸处理对镍基高温合金RR1000在700-800℃空气中氧化的影响。喷丸和未喷丸条件下的表面氧化物均由孤立的金红石颗粒组成，其最外表面是一层钛掺杂的氧化铬保护层。铝在合金中发生内氧化，在γ‘(名义上为Ni3(Al，Ti))剥蚀区形成氧化铝颗粒，但亚表面氧化物的形态在所考察的两种表面条件下不同。铬层增厚的动力学在大多数情况下是亚抛物线的，但在800℃下未喷丸的表面条件下，铬层的增厚动力学接近抛物线行为。与无钛的铬层相比，两种表面条件下的铬层的生长速度都有所提高。这种增强归因于铬层的钛掺杂增加了铬离子的扩散，但这种影响随着时间的推移而减弱，因为合金中的钛是贫化的。在800℃，未喷丸条件下，生长速率随曝光时间的下降不明显，这种影响似乎与铬层下形成(Ti，Ta)O2相有关。
The effect of shot-peening on the oxidation in air of the Ni-based superalloy RR1000 has been investigated over the temperature range 700–800 °C. The surface oxide in both peened and un-peened conditions consisted of isolated grains of rutile on the outermost surface beneath which was a protective Ti-doped chromia scale. Internal oxidation of aluminium occurred within the alloy with the formation of alumina particles within aγ′ (nominally Ni3(Al,Ti)) denuded zone but the morphology of the sub-surface oxides differed between the two surface conditions examined. The kinetics of thickening of the chromia layer were sub-parabolic in most cases but closely approached parabolic behaviour for the un-peened surface condition at 800 °C. An enhancement in the rate of chromia growth was found for both surface conditions compared with a Ti-free chromia layer. This enhancement has been attributed to increased Cr ion diffusion as a result of Ti-doping of the chromia layer but the effect is reduced over time because of Ti-depletion in the alloy. At 800 °C, in the un-peened condition, the reduction in growth rate with exposure time is much less marked and this effect seems to be associated with the formation of a (Ti,Ta)O2phase beneath the chromia layer.