Multiple strengthening mechanisms of cold-sprayed cBNp/NiCrAl composite coating
Multiple strengthening mechanisms of cold-sprayed cBNp/NiCrAl composite coating
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DOI：
10.1016/j.surfcoat.2011.04.065
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发表时间：
2011-07
影响因子：
5.4
通讯作者：
Xiao-Tao Luo;Guanjun Yang;Chang-jiu Li
中科院分区：
文献类型：
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作者：
Xiao-Tao Luo;Guanjun Yang;Chang-jiu Li
采用40 vol. %的cBN p/NiCrAl复合涂层，使用机械合金化复合粉末通过冷喷涂沉积cBN。采用扫描电子显微镜（SEM）、X射线衍射仪（XRD）和透射电子显微镜（TEM）对涂层的微观结构进行了表征。结果表明，纳米级和亚微米级的cBN颗粒均匀地分散在NiCrAl合金基体中。XRD和TEM分析结果表明，在冷喷涂过程中，NiCrAl基体的相和纳米晶结构从粉末到涂层都得到了完整的保留。硬度测试结果表明，致密的复合涂层表现出增加的维氏硬度为1175 Hv相比，退火的NiCrAl基体相的280 Hv。复合涂层的高硬度是由于颗粒弥散、加工硬化和晶粒细化的强化作用。从理论上估计了颗粒弥散、加工硬化和晶粒细化等强化机制对硬度的贡献。复合镀层的硬度估算值与实测值吻合较好。加工硬化强化是最主要的机制，其次是晶粒细化效应和弥散强化。
The cBNp/NiCrAl composite coating with 40 vol.% cBN was deposited by cold spray using a mechanically alloyed composite powder. The microstructure of the as-sprayed coating was characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that cBN particles in the size ranges of both nanometers and submicrometers were uniformly dispersed in NiCrAl alloy matrix. The XRD and TEM results revealed that the phase and nanocrystalline structures of the NiCrAl matrix were completely retained from the powder to coating during cold spraying. The hardness test results show that the dense composite coating exhibited an increased Vickers hardness of 1175 Hv compared with 280 Hv of the annealed NiCrAl matrix phase. The high hardness of the composite coating is attributed to the strengthening effects of particle dispersion, work hardening and crystal refinement. The contributions of the individual strengthening mechanisms, including particles dispersion, work hardening and crystal refinement, to hardness were theoretically estimated. The estimated hardness of the composite coating agreed well with the tested value. The work hardening strengthening is the most significant mechanism followed by crystal refinement effect and dispersion strengthening.