梯度纳米CrAlN复合涂层的承载失效行为研究

采用等离子体浸没离子注入与沉积技术,设计制备梯度纳米CrAlN复合涂层,利用X射线衍射仪、透射电子显微镜、纳米探针和理论计算分析等方法,系统研究涂层微观组织结构、力学性能和承载失效行为。研究表明:梯度纳米CrAlN涂层具有优异的纳米力学性能,并显著提高镁合金表面承载能力。动态承载过程中,接触载荷诱发金属Al和AlN界面高应力状态,Al金属层承受强烈的弹-塑性变形,当界面应力大于Al金属层屈服极限时,在靠近Al/AlN界面处萌生疲劳裂纹并最终导致涂层体系承载失效。本研究成果为软基体表面高强韧梯度复合涂层的结构设计提供重要理论依据。

Failure Mechanisms of Nanostructured Gradient CrAlN Composite Coatings: A Simulation and Experimental Study

The nano-structured gradient CrAlN composite coatings were synthesized by plasma immersion ion implantation and deposition for surface modification of Mg-based alloy.The influence of a dynamic load on the microstructures and bearing capacity of the as-deposited CrAlN coatings was investigated with X-ray diffraction.energy dispersive spectroscopy.transmission electron microscopy and by simulation in finite element method.The results show that the high stress at the Al/AlN interface and severe elastic-plastic deformations of Al-layer.originated from the contact load.explained the failure mechanisms.For instance.when the contact-load induced interfacial stress was stronger than the yield limit of Al.the fatigue cracks.occurring on the Al-side near the Al/AlN interface.accounted for failure or breakdown of the CrAlN coatings.We suggest that the results be of some basic and technological interest in surface modification of Mg-based alloy.