Can high strength and moderate ductility be combined in wear resistant coatings? A fundamental plasticity study of X2BC nanolaminates (X=Hf, Mo)

耐磨涂层能否将高强度和中等延展性结合起来？

• 批准号: 316303762
• 负责人: Professor Dr. Gerhard Dehm
• 金额: --
• 依托单位: Lehrstuhl für Werkstoffchemie (MCh)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/316303762?language=en
• 关键词: strength; moderate; ductility; combined; wear

In situ synchrotron X-ray diffraction experiments and small scale mechanical studies supported by electron microscopy will be conducted to delineate the relationship between coating stress and strain with the plastic behavior of Mo2BC. We seek to identify the fundamental mechanisms that govern the plastic behavior of X2BC nanolaminates (X=Hf, Mo) and compare these results to previously published and here obtained quantum mechanical predictions. Since our initial micro mechanical data support the notion of moderate ductility predicted by the quantum mechanical calculations this project aims at answering the following questions linking microstructural characteristics with the mechanical properties: 1. Does the microstructure of X2BC nanolaminate (X=Hf, Mo) coatings influence their mechanical behavior? The microstructure in coatings is controlled by the deposition parameters such as deposition temperature, deposition rate, and degree of ionization of the film forming species. We will deposit fully amorphous, fully crystalline coatings as well as films with various amorphous to crystalline phase fractions. TEM will be employed to determine the domain sizes of the crystalline and amorphous regions and, together with XRD, also the domain size of the crystalline regions for the fully crystalline films. In situ mechanical straining will be performed for different microstructures of X2BC nanolaminate (X=Hf, Mo) coatings. The influence of internal stresses and phase fraction and domain size on the mechanical behavior will be studied. Wafer curvature measurements are performed to assess the stress state of the as-deposited coatings. XRD is used to determine the stress (strain) in the crystalline regions of the coating and the mean sizes of the crystalline domains in the coatings. 2. What deformation mechanisms are active in X2BC nanolaminates (X=Hf, Mo)? Typically, layered solids such as MAX phases are known as plastically anisotropic materials. Upon loading, such solids deform by glide of basal plane dislocations. The formation of Kink Bands (KBs) was also reported as a consequence of the plastic anisotropy of the MAX phases. Based on post mortem TEM experiments, we aim for the characterization of the dislocations structure and its interaction with other microstructural features in order to identify and understand the deformation mechanism active in amorphous and nanocomposite (nanocrystals in an amorphous matrix) and fully crystalline X2BC coatings. 3. Does B/G and the Cauchy pressure serve as predictors for the plastic behavior of X2BC nanolaminates (X=Hf, Mo) While Mo2BC was predicted to behave moderately ductile, Hf2BC is expected - based on both, Cauchy pressure and B/G to be brittle. Hence, a comparative investigation of these two nanolaminate systems will shed light on the question as to the predictive capability of B/G and the Cauchy pressure and potential limits thereof for nanolaminates.

原位同步辐射X射线衍射实验和小规模的机械研究支持的电子显微镜将进行描绘涂层的应力和应变与Mo 2BC的塑性行为之间的关系。我们试图确定的基本机制，管理的X2 BC纳米层压材料（X=铪，钼）的塑性行为，并比较这些结果，以前发表的，在这里获得的量子力学预测。由于我们最初的微观力学数据支持量子力学计算预测的适度延展性的概念，因此该项目旨在回答以下问题，将微观结构特征与力学性能联系起来：1. X2 BC纳米叠层（X=Hf，Mo）涂层的微观结构是否影响其力学行为？涂层中的微观结构由沉积参数控制，例如沉积温度、沉积速率和成膜物质的电离度。我们将存款完全非晶，完全结晶涂层以及薄膜与各种非晶结晶相分数。将采用TEM来确定结晶和非晶区域的域尺寸，并且与XRD一起确定完全结晶膜的结晶区域的域尺寸。将对不同微观结构的X2 BC纳米叠层（X=Hf，Mo）涂层进行原位机械应变。将研究内应力、相分数和畴尺寸对力学行为的影响。进行晶片曲率测量以评估沉积涂层的应力状态。XRD用于确定涂层结晶区域中的应力（应变）和涂层中结晶域的平均尺寸。2.在X2 BC纳米层压材料（X=Hf，Mo）中，什么变形机制是活跃的？通常，层状固体如MAX相被称为塑性各向异性材料。在加载时，这种固体通过基面位错的滑移而变形。扭结带（KBs）的形成也被报道为MAX相的塑性各向异性的结果。基于事后TEM实验，我们的目标是表征位错结构及其与其他微观结构特征的相互作用，以识别和理解非晶和纳米复合材料（非晶基体中的纳米晶体）和全结晶X2 BC涂层中的变形机制。3. B/G和柯西压力是否用作X2 BC纳米层压材料（X=Hf，Mo）的塑性行为的预测因子。虽然预测Mo 2BC表现为适度的延展性，但基于柯西压力和B/G两者，预期Hf 2BC是脆性的。因此，这两个纳米层压系统的比较研究将揭示问题的预测能力的B/G和柯西压力和潜在的限制，其纳米层压。

项目成果

Thermal stability of nanocomposite Mo2BC hard coatings deposited by magnetron sputtering

• DOI: 10.1016/j.surfcoat.2018.06.006
• 发表时间: 2018-09
• 期刊: Surface and Coatings Technology
• 影响因子: 5.4
• 作者: S. Gleich;B. Breitbach;N. Peter;R. Soler;H. Bolvardi;J. Schneider;G. Dehm;C. Scheu

Correlative Experimental and Theoretical Investigation of the Angle-Resolved Composition Evolution of Thin Films Sputtered from a Compound Mo2BC Target

复合 Mo2BC 靶材溅射薄膜角度分辨成分演化的相关实验和理论研究

• DOI: 10.3390/coatings9030206
• 发表时间: 2019
• 期刊: Coatings
• 影响因子: 3.4
• 作者: J.-O. Achenbach;S. Mráz;D. Primetzhofer;J.M. Schneider
• 通讯作者: J.M. Schneider