| 引用本文: | 张晓民,李金刚,冯杰,马利锋,刘明霞.微桥法基体裂纹的线性模型及薄膜断裂应变测试∗[J].中国表面工程,2021,34(1):41~49 |
| Zhang Xiaomin,Li Jingang,Feng Jie,Ma Lifeng,Liu Mingxia.Linear Opening Model of Substrate Pre-crack and Determination of Fracture Strain of Thin Film during Tensile Testing of Microbridge Method[J].China Surface Engineering,2021,34(1):41~49 |
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| 摘要: |
| 薄膜断裂韧性测试方法的有效性取决于薄膜断裂应力和应变的精确测量。 采用高分辨扫描电镜对微桥法单晶硅片基体紧凑拉伸测试样品在测试过程中的基体裂纹张开量进行考察,发现基体裂纹尾部张开量( δs1 )在 9 ~ 35 μm 的范围内,与止裂孔边缘基体裂纹张开量(δs2 )存在良好的线性关系。 该试验结果表明存在一个位置恒定不变的虚拟裂纹尖端,使得基体裂纹张开量遵循线性关系。 基于该基体裂纹张开量的线性模型,可通过基体裂纹尾部张开量 δs1 的测量来间接获得薄膜的拉伸应变,进而计算薄膜在单轴拉伸和弯矩作用下的断裂韧性。 对 CuZr 非晶合金薄膜的标准化测试结果表明,薄膜断裂韧性 KIC 在 1. 08~ 1. 70 MPa·m1/ 2 的范围内变化,且与薄膜预制裂纹长度 a / W 存在一定的相关性,可能与非晶合金薄膜的应变软化机 |
| 关键词: 基体裂纹张开量 薄膜断裂应变 断裂韧性 CuZr 非晶合金薄膜 |
| DOI：10.11933/j.issn.1007-9289.20201220003 |
| 分类号:TB43 |
| 基金项目:国家自然科学基金资助项目(51671153,51771037) |
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| Linear Opening Model of Substrate Pre-crack and Determination of Fracture Strain of Thin Film during Tensile Testing of Microbridge Method |
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Zhang Xiaomin1, Li Jingang1, Feng Jie1, Ma Lifeng2, Liu Mingxia3
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1.School of Materials Science and Engineering, Xi’an University of Architecture and Technology, Xi’an 710055 , China;2.School of Aeronautics and Astronautics, Xi’an Jiaotong University, Xi’an 710049 , China;3.Shaanxi Key Laboratory of Surface Engineering and Remanufacturing, Xi’an University, Xi’an 710065 , China
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| Abstract: |
| Accurate measurement of critical strain and stress of a thin film when it fractures is crucial during testing of fracture tough- ness. In microbridge testing method, tensile displacement of a film is in consistent with the crack opening distance ( COD ) of sub- strate pre-crack at position where it anchors. However, a mathematical model for COD is difficult to deduce in mechanics due to the complex mechanical condition cause by the non half infinite boundary and the existence of an arresting hole near crack tip. High resolu- tion scanning electron microscope (HR-SEM) is used to examine the COD of substrate pre-crack. Both of the opening distance (δs1 ) at crack end and the opening distance (δs2 ) at the edge of arresting hole were accurately measured. Results show that δs1 and δs2 varies linearly when δs1 is in range of 9~ 35 μm. A stationary virtual crack tip was then hypothesized so that a linear relationship of COD of substrate pre-crack was subjected. Film tensile displacement can then be easily determined according to δs1 and the position the film anchored. A mathematical mode for fracture toughness of a film was derived via superposition of uni-axial tensile stress and the pure bending stress the film endured during tensile testing. A test for CuZr amorphous thin film was carried out, and 1. 08~ 1. 70 MPa·m1/ 2 of KIC is obtained. Results reveal that test values of KIC vary with the length of the pre-crack on film specimens(a / W), which may be resulted from the stain softening of amorphous metallic glass. |
| Key words: opening distance of the substrate crack critical strain of film fracture fracture toughness CuZr amorphous films |
