Pop-ins in Nanoindentations – the Initial Yield Point
Pop-ins in Nanoindentations – the Initial Yield Point
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DOI：
10.3139/ijmr-2001-0193
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发表时间：
2001-09
影响因子：
0.8
通讯作者：
M. Göken;M. Kempf
中科院分区：
文献类型：
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作者：
M. Göken;M. Kempf
摘要 在大多数金属和金属间材料上通过纳米压痕获得的载荷-位移曲线在载荷水平低于或大约 1 mN 时表现出不连续性或突然变化。这些弹出标记标志着样品表面从纯弹性载荷到塑性变形的急剧转变，因此对应于初始屈服点。在光滑表面上经常会观察到弹出现象，但在粗糙度较高的表面上则不会。表面上的阶梯边缘被讨论为初始屈服事件的位错源。由于弹出标记标志着从弹性变形到塑性变形的转变，因此弹性载荷部分可以通过赫兹接触模型来描述。几乎所有材料都观察到载荷-位移曲线的不连续性，给出了 c-BN、TiAl、Ti3Al、Cu 和 Mo5SiB2 的示例。在钼样品上，有时仅在载荷-位移曲线的卸载部分发现不连续性。讨论了不同弹出效果的起源。
Abstract The load – displacement curves as obtained by nanoindentations on most metallic and intermetallic materials show discontinuities or pop-ins at load levels below or around 1 mN. These pop-ins mark a sharp transition from pure elastic loading to a plastic deformation of the specimen surface, thus correspond to an initial yield point. On smooth surfaces pop-ins are observed frequently, but not on surfaces with a high roughness. Step edges on the surface are discussed as dislocation sources for the initial yield events. Since the pop-ins mark the transition from elastic to plastic deformation, the elastic loading part can be described by the Hertzian contact model. Discontinuities in the load –displacement curves are observed on nearly all materials, examples are given for c-BN, TiAl, Ti3Al, Cu, and Mo5SiB2. On Mo samples, discontinuities are found sometimes only in the unloading part of the load – displacement curves. The origin of the different pop-in effects are discussed.