Plasma nitridation of a novel Ni–10.8 wt.%Cr nanocomposite
Plasma nitridation of a novel Ni–10.8 wt.%Cr nanocomposite
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DOI：
10.1016/j.actamat.2007.01.018
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发表时间：
2007-05
期刊：
影响因子：
9.4
通讯作者：
Jianglin Zhao;X. Peng;Yanbo Wang;Fu-Xin Wang
中科院分区：
文献类型：
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作者：
Jianglin Zhao;X. Peng;Yanbo Wang;Fu-Xin Wang
Ni-10.8Cr纳米复合材料（重量%），采用纳米复合电沉积法制备了由纳米晶Ni基体（平均晶粒尺寸为60 nm）和分散的Cr纳米颗粒（平均颗粒尺寸为42 nm）组成的纳米复合电沉积材料。这种独特的结构使纳米复合材料在560°C等离子体氮化10 h时形成了双层氮化层。外层（约50μm厚）析出纳米级CrN（<100 nm），其尺寸随氮化深度的增加而增加，数量却随氮化深度的增加而减少（遵循Böhm-Kahlweit模式）。内层（约1.5 μm厚）为粗大的氮化物沉淀（100- 200 nm），几乎连成一片。与成分相似但微观结构不同的Ni-10 Cr合金（平均晶粒尺寸：30μm）相比，纳米复合材料中大大增强的氮化动力学主要与以下事实有关：根据使用经典瓦格纳方法的处理，大量晶界显著增加了氮渗透性。还研究了纳米硬度分布与纳米复合材料中氮化区显微结构的关系。
A Ni–10.8Cr nanocomposite (by wt.%), consisting of nanocrystalline Ni matrix (mean grain size: 60nm) and dispersed Cr nanoparticles (mean particle size: 42nm), has been synthesized by nanocomposite electrodeposition. The unique structure causes the nanocomposite to form a double-layered nitrided zone during plasma nitridation at 560°C for 10h. The outer layer (∼50μm thick) precipitates nanometer-sized CrN (<100nm), which increased in size but decreased in number with increasing nitridation depth (following Böhm–Kahlweit’s mode). The inner layer (∼5μm thick) exhibits larger-coarsened nitride precipitates (100–200nm) which almost link together. The greatly enhanced nitriding kinetics in the nanocomposite compared to a compositionally similar but microstructurally different Ni–10Cr alloy (mean grain size: 30μm) is mainly associated with the fact that the numerous grain boundaries dramatically increase the nitrogen permeability, according to the treatment using a classical Wagner’s approach. The nanohardness profile in relation to the microstructure of the nitrided zone in the nanocomposite has also been investigated.