Micromachining Imposed Subsurface Plastic Deformation in Single-Crystal Aluminum

2020 ◽  
Author(s):  
Sudhanshu Nahata ◽  
Marzyeh Moradi ◽  
Yoosuf N. Picard ◽  
Nithyanand Kota ◽  
O. Burak Ozdoganlar
2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Jun Ding ◽  
Lu-sheng Wang ◽  
Kun Song ◽  
Bo Liu ◽  
Xia Huang

The crack propagation process in single-crystal aluminum plate (SCAP) with central cracks under tensile load was simulated by molecular dynamics method. Further, the effects of model size, crack length, temperature, and strain rate on strength of SCAP and crack growth were comprehensively investigated. The results showed that, with the increase of the model size, crack length, and strain rate, the plastic yield point of SCAP occurred in advance, the limit stress of plastic yield decreased, and the plastic deformability of material increased, but the temperature had less effect and sensitivity on the strength and crack propagation of SCAP. The model size affected the plastic deformation and crack growth of the material. Specifically, at small scale, the plastic deformation and crack propagation in SCAP are mainly affected through dislocation multiplication and slip. However, the plastic deformation and crack propagation are obviously affected by dislocation multiplication and twinning in larger scale.


2007 ◽  
Vol 1049 ◽  
Author(s):  
Yongjiang Huang ◽  
Nursiani Indah Tjahyono ◽  
Jun Shen ◽  
Yu Lung Chiu

AbstractThis paper summarises our recent cyclic nanoindentation experiment studies on a range of materials including single crystal and nanocrystalline copper, single crystal aluminium and bulk metallic glasses with different glass transition temperatures. The unloading and reloading processes of the nanoindentation curves have been analysed. The reverse plasticity will be discussed in the context of plastic deformation mechanisms involved. The effect of loading rates on the mechanical properties of materials upon cyclic loading will also be discussed.


2021 ◽  
Author(s):  
Lianmin Yin ◽  
Yifan Dai ◽  
Hao Hu

Abstract In order to obtain ultra-smooth surfaces of single-crystal silicon in ultra-precision machining, an accurate study of the deformation mechanism, mechanical properties, and the effect of oxide film under load is required. The mechanical properties of single-crystal silicon and the phase transition after nanoindentation experiments are investigated by nanoindentation and Raman spectroscopy, respectively. It is found that pop-in events appear in the theoretical elastic domain of single-crystal silicon due to the presence of oxide films, which directly leads the single crystal silicon from the elastic deformation zone into the plastic deformation zone. In addition, the mechanical properties of single-crystal silicon are more accurately measured after it has entered the full plastic deformation.


The influence of very small quantities of impurity on the critical shear stress of metal single crystals has an important bearing on the mechanism of their plastic deformation. For investigations in this field, mercury is a very suitable metal: its impurity content can easily be reduced to an extremely low level (Hulett 1911) and it contains no dissolved gases (Hulett 1911). Also, as first pointed out by Andrade (1914), single crystal wires of this metal can be prepared without difficulty. The low melting point of mercury (-38∙8° C.) is far from being a disadvantage. The crystals can be maintained at -60° C., and at a temperature so near the melting point the thermal agitation may be expected to accentuate phenomena not observable at lower temperatures, if such agitation plays the important part in the mechanism of glide ascribed to it (Taylor 1934; Polanyi 1934; Orowan 1934). As a possible instance of this, the experiments to be described have revealed the existence of a preliminary “set” preceding the true plastic yield. Widely differing forms of slip band have also been observed, and are described elsewhere (Greenland 1937). It is hoped that these results will throw further light on the mechanism of glide.


2013 ◽  
Vol 568 ◽  
pp. 83-87 ◽  
Author(s):  
T.K. Liu ◽  
G.L. Wu ◽  
C.K. Liu ◽  
Z.H. Nie ◽  
T. Ungár ◽  
...  

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