scholarly journals Mechanical Behavior of Undoped n-Type GaAs under the Indentation of Berkovich and Flat-Tip Indenters

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1192 ◽  
Author(s):  
Lixia Xu ◽  
Lingqi Kong ◽  
Hongwei Zhao ◽  
Shunbo Wang ◽  
Sihan Liu ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Brittle Materials ◽  
Wing Shape ◽  
Gaas Surface ◽  
Surface Material ◽  
Berkovich Indenter ◽  
Fracture Characteristics ◽  
Slip Bands ◽  
Mechanical Machining ◽  
Depth Curves

In this research, the mechanical behavior of undoped n-type GaAs was investigated by nanoindentation experiments using two types of indenters—Berkovich and flat-tip—with force applied up to 1000 mN. From the measured force-depth curves, an obvious pop-in phenomenon occurred at force of 150 mN with the flat-tip indenter representing elastic–plastic transition. The Young’s modulus and hardness of GaAs were calculated to be 60–115 GPa and 6–10 GPa, respectively, under Berkovich indenter. Based on the observation of indent imprints, the fracture characteristics of GaAs were also discussed. A recovery of crack by the next indentation was observed at 1000 mN with Berkovich indenter. In the case of flat-tip indentation, however, surface material sank into a wing shape from 400 mN. In this sinking region, a density of fork-shaped sinking, slip lines, and crossed pits contributed to the slip bands, and converging crossed twinning deformations inside the GaAs material were generated. Since cracks and destructions on GaAs surface took place more easily under the flat-tip indentation than that of Berkovich, a machining tool with a sharp tip is recommended for the mechanical machining of brittle materials like GaAs.

Application of TEM to Deformation, Wear, and Fracture of Ceramics

1974 ◽  
Vol 32 ◽  
pp. 472-473
Author(s):  
B. J. Hockey
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Brittle Materials ◽  
High Temperature Strength ◽  
Wide Range ◽  
Corrosive Environments ◽  
Further Development

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.

scholarly journals Cracking During Nanoindentation and its Use in the Measurement of Fracture Toughness

1994 ◽  
Vol 356 ◽  
Author(s):  
D. S. Harding ◽  
W. C. Oliver ◽  
G. M. Pharr
Keyword(s):  
Thin Film ◽  
Fracture Toughness ◽  
Small Volume ◽  
Brittle Materials ◽  
Empirical Method ◽  
Berkovich Indenter ◽  
Empirical Constant ◽  
Cube Corner ◽  
Semi Empirical ◽  
Radial Cracks

AbstractResults of an investigation aimed at developing a technique by which the fracture toughness of a thin film or small volume can be determined in nanoindentation experiments are reported. The method is based on the radial cracking which occurs when brittle materials are deformed by a sharp indenter such as a Vickers or Berkovich diamond. In microindentation experiments, the lengths of radial cracks have been found to correlate reasonably well with fracture toughness, and a simple semi-empirical method has been developed to compute the toughness from the crack lengths. However, a problem is encountered in extending this method into the nanoindentation regime with the standard Berkovich indenter in that there are well defined loads, called cracking thresholds, below which indentation cracking does not occur in most brittle materials. We have recently found that the problems imposed by the cracking threshold can be largely overcome by using an indenter with the geometry of the corner of a cube. For the cube-corner indenter, cracking thresholds in most brittle materials are as small as 1 mN (∼ 0.1 grams). In addition, the simple, well-developed relationship between toughness and crack length used for the Vickers indenter in the microindentation regime can be used for the cube-corner indenter in the nanoindentation regime provided a different empirical constant is used.

Description of Unloading Behavior of Berkovich Nanoindentation

2007 ◽  
Vol 280-283 ◽  
pp. 1757-1760 ◽  
Author(s):  
He Zhuo Miao ◽  
Jiang Hong Gong ◽  
Zhi Jian Peng
Keyword(s):  
Experimental Data ◽  
Power Law ◽  
Contact Stress ◽  
Brittle Materials ◽  
Physical Significance ◽  
Berkovich Indenter ◽  
New Approach ◽  
Load Displacement

We established a new expression to describe the nanoindentation unloading data by assuming that the Berkovich indenter behaves as a conical punch, rather than a paraboloid punch, and properly considering the effect of residual contact stress on the unloading load-displacement relation. The validity of this new approach was confirmed by analyzing the experimental data obtained for a series of brittle materials. It was shown that, compared with the generally adopted power law, this new expression has much clearer physical significance.

The Surface Quality Experimental Analysis of Rotary Ultrasonic Machining

2013 ◽  
Vol 419 ◽  
pp. 348-354 ◽  
Author(s):  
Chao Liang Xu ◽  
Xiao Hua Tang ◽  
Tian Yu Xia
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Brittle Materials ◽  
Zirconia Ceramic ◽  
Ultrasonic Machining ◽  
Rotary Ultrasonic Machining ◽  
Ultrasonic Machine ◽  
Mechanical Machining ◽  
Better Than

Rotary ultrasonic machining (RUM) is widely used for machining virous kinds of hard-brittle materials. This article aims to study ultrasonic machining surface quality of zirconia ceramic, low-carbonsteel boltwith self-developed rotary ultrasonic machine. The surface roughness could be detected and observed by Taylor Hobson surface roughness instrument and Keyence microscope.The experimental resultsshow that the surface quality achieved by rotary ultrasonic machining is better than bytraditional mechanical machining. Rotary ultrasonic machininghas advantages for machining hard-brittle materials.

PLASTICITY CHARACTERISTICS OBTAINED THROUGH INSTRUMENTAL INDENTATION

2007 ◽  
Vol 1049 ◽  
Author(s):  
Yuliy Milman ◽  
Sergey Dub ◽  
Alex Golubenko
Keyword(s):  
Mechanical Behavior ◽  
Crystal Structures ◽  
Mechanical Tests ◽  
Berkovich Indenter ◽  
Crystalline Materials ◽  
Plasticity Characteristic ◽  
Microhardness Testing ◽  
Different Types ◽  
Instrumental Indentation

AbstractThe nanohardness and microhardness testing of crystalline materials with different types of interatomic bonds and different crystal structures was performed with Berkovich indenter.The plasticity characteristics for crystalline materials with different types of interatomic bonds and different crystalline structures were determined by microindentation and by nanoindentation. The relation between these characteristics and parameters of material (Meyer hardness, Young's modulus and Poisson's ratio) was assigned. Plasticity characteristic may be used for characterization of mechanical behavior of materials which are brittle at standard mechanical tests and for coatings.

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