Kholkhujaev Jasurkhuja, Maculotti Giacomo, Genta Gianfranco, Galetto Maurizio
Department of Management and Production Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Turin, Italy.
Department of Mechanical and Aerospace Engineering, Turin Polytechnic University in Tashkent, Kichik Halka Yuli, 17, Tashkent 100095, Uzbekistan.
Materials (Basel). 2023 Jun 8;16(12):4262. doi: 10.3390/ma16124262.
The Instrumented Indentation Test (IIT) mechanically characterizes materials from the nano to the macro scale, enabling the evaluation of microstructure and ultra-thin coatings. IIT is a non-conventional technique applied in strategic sectors, e.g., automotive, aerospace and physics, to foster the development of innovative materials and manufacturing processes. However, material plasticity at the indentation edge biases the characterization results. Correcting such effects is extremely challenging, and several methods have been proposed in the literature. However, comparisons of these available methods are rare, often limited in scope, and neglect metrological performance of the different methods. After reviewing the main available methods, this work innovatively proposes a performance comparison within a metrological framework currently missing in the literature. The proposed framework for performance comparison is applied to some available methods, i.e., work-based, topographical measurement of the indentation to evaluate the area and the volume of the pile-up, Nix-Gao model and the electrical contact resistance (ECR) approach. The accuracy and measurement uncertainty of the correction methods is compared considering calibrated reference materials to establish traceability of the comparison. Results, also discussed in light of the practical convenience of the methods, show that the most accurate method is the Nix-Gao approach (accuracy of 0.28 GPa, expanded uncertainty of 0.57 GPa), while the most precise is the ECR (accuracy of 0.33 GPa, expanded uncertainty of 0.37 GPa), which also allows for in-line and real-time corrections.
仪器化压痕测试（IIT）可从纳米尺度到宏观尺度对材料进行力学表征，从而能够评估微观结构和超薄涂层。IIT是一种应用于战略领域（如汽车、航空航天和物理学）的非常规技术，以促进创新材料和制造工艺的发展。然而，压痕边缘处的材料塑性会使表征结果产生偏差。校正此类影响极具挑战性，文献中已提出了几种方法。然而，对这些现有方法的比较很少见，通常范围有限，并且忽略了不同方法的计量性能。在回顾了主要的现有方法之后，本研究创新性地提出了一种在文献中目前缺失的计量框架内进行性能比较的方法。所提出的性能比较框架应用于一些现有方法，即基于功的方法、压痕的形貌测量以评估堆积面积和体积、Nix-Gao模型以及电接触电阻（ECR）方法。考虑到校准参考材料以建立比较的可追溯性，比较了校正方法的准确性和测量不确定度。根据方法的实际便利性对结果进行的讨论表明，最准确的方法是Nix-Gao方法（准确度为0.28 GPa，扩展不确定度为0.57 GPa），而最精确的是ECR方法（准确度为0.33 GPa，扩展不确定度为0.37 GPa），该方法还允许进行在线和实时校正。
