Nanostructured metallic multilayers with carefully designed mechanical and functional properties are omnipresent in cutting edge technological applications. To ensure the mechanical integrity of such coatings, the Mode I critical Stress Intensity Factor K_IC is used to quantify their fracture toughness in order to avoid material failure by appropriate design. In this article, we present a novel approach for the K_IC determination of thin and ultrathin films on compliant substrate, based on micro-displacement field analysis using Digital Image Correlation within SEM. Using this method, K_IC of a Cu/W nano-multilayer with a total coating thickness of 240 nm was determined as ${\mathrm{K}}_{\text{IC}}=4.8\pm 0.05\text{MPa}\sqrt{\mathrm{m}}$, showing excellent agreement with the values published for comparable systems in the literature. To verify the validity of the chosen approach, two independent finite element simulations were employed, thus revealing the role and effect of the compliant substrate on the stress and displacement fields arising around the crack tip in thin films.

具有尖端设计的机械和功能特性的纳米结构金属多层材料在尖端技术应用中无处不在。为了确保此类涂层的机械完整性，使用I型临界应力强度因子K _IC来量化其断裂韧性，以便通过适当的设计避免材料失效。在本文中，我们基于使用SEM中的数字图像相关性进行的微位移场分析，提出了一种新的方法来测定柔性基板上的薄膜和超薄膜的K _IC。使用此方法，将总涂层厚度为240 nm的Cu / W纳米多层膜的K _IC确定为${\mathrm{ķ}}_{\text{我知道了}}=4.8\pm 0.05\text{兆帕}\sqrt{\mathrm{米}}$，表明与文献中可比系统的发布值具有极好的一致性。为了验证所选择方法的有效性，采用了两个独立的有限元模拟，从而揭示了柔性基底对薄膜裂纹尖端周围应力场和位移场的作用和影响。