Oxidation behavior of a Ni3Al PM alloy
Oxidation behavior of a Ni3Al PM alloy
复制标题
DOI：
10.1007/bf01675266
复制
发表时间：
1997-08
影响因子：
2.2
通讯作者：
P. Pérez;J. L. González-carrasco;P. Adeva
中科院分区：
文献类型：
--
作者：
P. Pérez;J. L. González-carrasco;P. Adeva
通过不连续恒温试验，在535°至1020°C温度范围内暴露长达150小时，研究了掺硼Ni 3Al粉末冶金（PM）合金的氧化行为。氧化动力学的特征是氧化速率急剧下降在约730°C，这与氧化机制的变化有关。在730°C以下，氧化皮表现出外部NiO层和由氧化铝在稀释的Ni-Al固溶体中的精细分散体组成的内部氧化区。在这两层之间可以观察到非常薄的镍层。在730°C以上，观察到由外部NiO层、取决于温度由镍和铝氧化物或NiAl 2 O 4的混合物组成的中间层和Al 2 O3内层组成的三层氧化皮，这是较高抗氧化性的原因。在较高温度下的氧化导致在垢/金属界面处形成大量空隙，这导致粘附性差的垢。值得注意的是，在早期氧化阶段的规模的特点是平面界面。粗糙的空气/规模，特别是规模/金属界面后，长期暴露在低温范围内或短时间后，在较高的温度可能与形成的内部Al 2 O3层的晶界，有利于氧气渗透通过晶粒内部。
The oxidation behavior of a Ni3Al powder-metallurgical (PM) alloy doped with boron was investigated by means of discontinuous isothermal tests in the temperature range of 535° to 1020°C for exposures of up to 150 hr. The oxidation kinetics were characterized by a sharp decrease in the oxidation rate at about 730°C which is associated with a change in the oxidation mechanism. Below 730°C, the scale exhibited an outer NiO layer and an internal-oxidation zone consisting of a fine dispersion of alumina in a diluted Ni-Al solid solution. Between these two layers a very thin layer of nickel could be observed. Above 730°C, a three-layered scale was observed consisting of an outer NiO layer, an intermediate layer that depending on temperature consisted of a mixture of nickel and aluminum oxides or NiAl2O4, and an inner layer of Al2O3, which accounts for the higher oxidation resistance. Oxidation at the higher temperatures resulted in extensive void formation at the scale/metal interface which led to poorly adherent scales. It is worth noting that at the early oxidation stage the scale was characterized by planar interfaces. Roughening of the air/scale and, specially, the scale/metal interfaces after long exposures at the low-temperature range or after short times at higher temperatures could be related to the formation of the inner Al2O3layer at the grain boundaries which favor oxygen penetration through the grain interior.