On the formation of serrated grain boundaries and fan type structures in an advanced polycrystalline nickel-base superalloy
On the formation of serrated grain boundaries and fan type structures in an advanced polycrystalline nickel-base superalloy
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DOI：
10.1016/j.jmatprotec.2008.03.008
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发表时间：
2009-01
影响因子：
6.3
通讯作者：
R. J. Mitchell;H. Y. Li;Zhenyu Huang
中科院分区：
文献类型：
--
作者：
R. J. Mitchell;H. Y. Li;Zhenyu Huang
对先进多晶镍基高温合金中锯齿状晶界和扇形组织的形成进行了广泛的研究，并将其与热历史联系起来。晶界锯齿的发展与固溶热处理温度的冷却速率有关。发现较慢的冷却速率导致越来越多的二次γ′受到冲击而形成更复杂的晶界。在晶界附近的γ′分布也有细微的差异，特别是它们在尺寸、形态和化学上表现出不同，这是晶粒内位置的函数，所有这些都在论文中有所报道。在合金中发现扇形结构的形成与冷却速率无关，尽管它们的尺寸和体积分数随着冷却速率的降低而增加。这些组织的存在对晶界的总长度和锯齿化程度有影响。扇形结构表现出典型的枝晶形态，并在合金内部的少量相上成核。
The formation of serrated grain boundaries and fan-type structures in an advanced polycrystalline nickel-base superalloy has been extensively studied and linked to the thermal history. The development of grain boundary serrations has been quantitatively linked to the cooling rate from the solution heat treatment temperature. Slower cooling rates were found to result in more convoluted grain boundaries formed as a result of impingement of growing secondary γ′. Subtle differences were also noted in the γ′ distributions in the vicinities of the grain boundaries, in particular they exhibit differences in size, morphology and chemistry as a function of location within the grain, all of which are reported in the paper. Fan-type structures were found to form in the alloy, irrespective of the cooling rate employed, although their size and volume fraction increased with a decrease in cooling rate. The presence of these structures is shown to impact upon the total length of grain boundary and the degree of serration. The fan-type structures exhibit a typical dendritic morphology and were found to nucleate on minor phases present within the alloy.