【作者】 黄勇力；

【导师】 周益春；

【作者基本信息】 湘潭大学 ， 材料物理与化学， 2006， 硕士

【摘要】 近年来,薄膜科学愈来愈受到重视,对其力学性能的研究已成为热门领域。纳米压痕测试技术作为一种测量薄膜材料力学性能的方法,以其高度的位移分辨率、超低载荷及连续测量能力倍受青睐。本文以纳米压痕法结合量纲分析及有限元方法来测量薄膜材料的应力-应变关系。本文的工作主要分为两个部分:第一部分是建立用纳米压痕法测量薄膜应力-应变关系的理论框架;第二部分是实际测定电沉积镍镀层的应力-应变关系。本文首先介绍了本课题的研究背景和研究现状,对纳米压痕技术进行了较为详细的叙述,阐明了我们选取本课题的依据。接着按如下思路归纳出了测量脆性薄膜/韧性基底、脆性薄膜/脆性基底、韧性薄膜/脆性基底以及韧性薄膜/韧性基底四种膜/基组合材料力学性能的理论框架:首先用量纲分析的方法将纳米压痕过程与被测材料的力学性能,如弹性模量、屈服强度及应变硬化指数等联系起来,建立起两者之间简单的无量纲函数关系的结构形式,其次用有限元方法模拟压头压入材料的过程,分析得到无量纲函数的具体形式,最后根据实测的载荷-位移曲线确定所需测量的力学性能参量。本文另一主要工作是详细介绍了用纳米压痕法测量电沉积镍镀层应力-应变关系的过程。用ABAQUS有限元软件模拟了Berkovich压头压入镍镀层1000nm的压痕过程,结合量纲分析得到的无量纲函数关系式与实测的载荷-位移曲线,求得了电沉积镍镀层的屈服强度与应变硬化指数。本文还引用了马德军用纳米压痕法测量韧性薄膜/脆性基底组合材料的力学性能的工作。根据这两个实例,我们证明了该理论框架的可行性。更多还原

【Abstract】 Recently, more and more attentions have been paid to thin films, and research of the mechanical properties of thin films gets to be a hot subject. As a method to evaluate the mechanical properties of thin films, nanoindentation technique is in the popularity for its high displacement resolution, ultra low load and the capability of continuous measurement. In this master thesis, the stress-strain relationships of thin films were measured by nanoindentation combined with dimensional analysis and finite element method.Two main parts are contained in this master thesis. In the first part, a theory frame was established to extract the stress-strain relationships of thin films by nanoindentation. In the second part, the stress-strain relationship of electrodeposited nickel coating was measured.At the beginning of this thesis, related research background and research status were introduced, then nanoindentation technology and the background of this master thesis were interpreted detailedly. A theory frame to measure the mechanical properties of four kinds of film/substrate systems, namely, brittle film on tough substrate, brittle film on brittle substrate, tough film on brittle substrate and tough film on tough substrate, was established. We can get the mechanical properties of thin films with following steps: first, dimensional analysis was applied to derive the relationship between indentation and mechanical properties of material, such as Young’s modulus, yield strength, strain hardening exponent etc. Then, the indentation process was simulated by finite element method. At last, the mechanical parameters were extracted from the true load-displacement curves. Another important work in this master thesis is the detailed introduction of extracting stress-strain relationship of electrodeposited nickel coating from nanoindentation. ABAQUS was used to simulate the process that the Berkovich indenter indented into the electrodeposited nickel coating about 1000nm, then according to the real Load-Depth curves got in the nanoindentation experiments and the dimensionless functions, the yield strength and strain hardening exponent were figured out. The work measuring the mechanical properties of tough film on brittle substrate finished by Ma Dejun was cited in this thesis. The feasibility of this theory frame was proved by both of the examples.更多还原