Abstract An in-depth investigation of the structure, properties, scratch adhesion characteristics of graded Cr-CrN-Cr (1-x) Al x N coatings synthesized onto M42 steel substrates using closed – field unbalanced magnetron sputtering (CFUBMS) was carried out. Advanced microscopy (scanning and transmission electron microscopy), focused ion beam (FIB) imaging, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and micro–scratch tests was used to investigate the microstructure, mechanical properties and scratch performance as a function of Al content. FIB and TEM investigations revealed that the coatings exhibited a distinct structure; i.e., an adhesive Cr layer, a CrN transition layer and a graded CrAlN top layer with a face centered cubic (FCC) B1 structure. A columnar morphology was exhibited by the coatings and the dimensions of the columnar grains decreased with increasing Al content. Residual stress measurements, obtained from the XRD – sin 2 ψ method, revealed increasing compressive stresses with increasing Al content. Furthermore, nanoindentation tests showed an increase in mechanical properties, fracture toughness index (H/E) and plastic deformation resistance (H 3 /E 2 ) as the Al content increased, accompanied by a decrease in the critical load, L C , during scratch testing implying a decrease in scratch toughness.

中文翻译：

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梯度Cr-CrN-Cr (1-x) Al x N涂层的结构、性能、抗划伤性和变形行为研究

摘要 对使用闭场不平衡磁控溅射 (CFUBMS) 合成到 M42 钢基材上的渐变 Cr-CrN-Cr (1-x) Al x N 涂层的结构、性能和划痕粘附特性进行了深入研究。高级显微镜（扫描和透射电子显微镜）、聚焦离子束（FIB）成像、X 射线光电子能谱（XPS）、X 射线衍射（XRD）和微划痕测试用于研究微观结构、机械性能和划痕性能与铝含量的函数关系。FIB 和 TEM 研究表明涂层表现出独特的结构；即，粘合 Cr 层、CrN 过渡层和具有面心立方 (FCC) B1 结构的渐变 CrAlN 顶层。涂层表现出柱状形态，柱状晶粒的尺寸随着铝含量的增加而减小。从 XRD – sin 2 ψ 方法获得的残余应力测量结果表明，随着 Al 含量的增加，压应力也增加。此外，纳米压痕测试表明，在划痕测试期间，随着 Al 含量的增加，机械性能、断裂韧性指数 (H/E) 和塑性变形抗力 (H 3 /E 2 ) 增加，同时临界载荷 LC 降低意味着划痕韧性降低。