Microstructure Based Structure-Property Relationships for the Design of Thin Films and Composite Coatings by Multiscale Materials Modeling

Abstract

Integrated Computational Materials Engineering (ICME) is the next generation methodology for the discovery, development, and deployment of material solutions. ICME refers to tackling materials science and engineering problems by way of merging materials modeling exploiting High-Performance Computing (HPC), experimental and characterization activities, as well as data and its analytics in the solution process and utilizing this toolset to deliver better performing innovative material solutions faster. A crucial element in ICME is the application paradigms of multiscale materials modeling, such as the widely adopted Process-Structure-Properties-Performance (PSPP) approach. The PSPP construct itself is a common frame for experimentalists and modelers alike to convey materials problems from discovery to deployment in terms of the typical progression of how to develop a new material or material solution. To realize PSPP in practice for modeling, workflows are required. These workflows consist of interacting multiscale materials modeling objects, which are interfaced to support the solution of an ICME problem. Commonly, such workflows consist of multiscale models of material manufacturing (processing), digital representation of the following material structure, modeling the properties of the structure in question (for example engineering material properties), and evaluating the performance of the material solution that links the material to its application environment. The PSPP chain as such establishes causal relations from material processing all the way to its application performance. Since optimization-wise this is an imperfect construct, Material Informatics (MI) deals with managing and analyzing the data, ultimately targeting the solution of the coveted inverse problem, where a material is discovered and designed based on its performance requirements and optimized for example with respect to the affiliated costs. The goal is to deploy a material that satisfies the functionality requirements set for the product performance.<br/><br/>Applications of ICME began from the need for extreme performance, for example involving material solutions for aerospace applications. Another high end application involves surfaces and coatings for wear resistance and lubrication, engaging material challenges for example in transportation or highly abrasive environments such as mining applications. This is also the domain of the current work, i.e., how to systematically develop better wear resistant surfaces and coatings. The specific challenge is the development, implementation and validation of ICME workflows for microstructure founded design of coatings and thin films for improved wear resistance. Within this scope, the current work develops a multiscale framework for modeling the microstructure and surface topography of complex multiphase coating microstructures and thin films, employing means to model realistic material microstructural morphologies containing also a composite interface character. The behavior of thin solid coatings under sliding abrasive loading is studied, and the possibilities of utilizing Cohesive Zone Modeling (CZM) directly in the modeling of film rupture are established. Next, the focus turns toward the introduction of the microstructural modeling of either thin or composite coating solutions, for which the computational methodologies are developed, implemented and validated. The analyzed cases consider primarily cemented carbide microstructures under abrasive tribological loading conditions. The computational methodology is developed further to increase realism with respect to modeling material interfaces, where Finite Element (FE) based models are interfaced to a Phase Field (PF) based modeling of rapid solidification microstructures as a result of material processing. After establishing a realistic enough description of the composite microstructure, the focus turns to introducing a modeling solution capable of addressing surface roughness and topography, in relation to other coating characteristics. This introduces a methodology enabling modeling of both the coating topography, its microstructure, interfaces with the bulk substrate, and the microstructure of the substrate itself. ICME workflows are discussed, outlined, and set up for the design of wear resistant surfaces utilizing the PSPP principle as a basis, considering especially the microstructure to product linkage in a bottom-up manner. The various use cases support the notion that ICME already provides added value to the solution of tribological problems and material related challenges by adding knowledge for solving problems otherwise difficult and costly to handle. Furthermore, the greatest impact and improved quality of results are obtained when both experimental and modeling approaches are used concurrently and not viewed as alternatives or competitors.