Dependence of room temperature fracture strength on strain-rate in sapphire

In this paper, the effects of different strain rate(1×10-5 s-1, 5×10-5 s-1, 1×10-4 s-1, 5×10-4 s-1, 1×10-3 s-1) and aspect ratio(1:1, 1.5:1, 2:1, 2.5:1, 3:1) on mechanical properties of Zr-based metallic glasses at room temperature were investigated. The results indicate that as the strain rate increases, the plastic strain and compressive strength of the specimens gradually decrease. The specimen with the strain rate of 1×10-5 s-1 exhibits the higher plastic strain of 10.25 %, compressive strength of 2002 MPa and fracture strength of 1999 MPa. In addition, accompanied with the increase in aspect ratio, the plastic strain of the specimens declines from 25.42 % to 1.97 %, meanwhile, the compressive strength and fracture strength of the specimens also present declining trend.

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The effect of strain rates on tensile deformation of ultrafine-grained copper

International Journal of Modern Physics B ◽

10.1142/s0217979217440143 ◽

2017 ◽

Vol 31 (16-19) ◽

pp. 1744014

Author(s):

M. Li ◽

Q. W. Jiang

Keyword(s):

Strain Rate ◽

Deformation Behavior ◽

Room Temperature ◽

Tensile Deformation ◽

Strain Rates ◽

Roll Bonding ◽

Fracture Elongation ◽

Tensile Deformation Behavior ◽

Ultrafine Grained ◽

Flow Stress Level

Tensile deformation behavior of ultrafine-grained (UFG) copper processed by accumulative roll-bonding (ARB) was studied under different strain rates at room temperature. It was found that the UFG copper under the strain rate of 10[Formula: see text] s[Formula: see text] led to a higher strength (higher flow stress level), flow stability (higher stress hardening rate) and fracture elongation. In the fracture surface of the sample appeared a large number of cleavage steps under the strain rate of 10[Formula: see text] s[Formula: see text], indicating a typical brittle fracture mode. When the strain rate is 10[Formula: see text] or 10[Formula: see text] s[Formula: see text], a great amount of dimples with few cleavage steps were observed, showing a transition from brittle to plastic deformation with increasing strain rate.

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Local Investigations of the Mechanical Properties of Ultrafine Grained Metals by Nanoindentations

Materials Science Forum ◽

10.4028/www.scientific.net/msf.503-504.31 ◽

2006 ◽

Vol 503-504 ◽

pp. 31-36 ◽

Cited By ~ 17

Author(s):

Johannes Mueller ◽

Karsten Durst ◽

Dorothea Amberger ◽

Matthias Göken

Keyword(s):

Mechanical Properties ◽

Strain Rate ◽

Strain Rate Sensitivity ◽

Room Temperature ◽

Rate Sensitivity ◽

Strain Rates ◽

Fcc Metals ◽

Angular Pressing ◽

Ultrafine Grained ◽

Indentation Strain

The mechanical properties of ultrafine-grained metals processed by equal channel angular pressing is investigated by nanoindentations in comparison with measurements on nanocrystalline nickel with a grain size between 20 and 400 nm produced by pulsed electrodeposition. Besides hardness and Young’s modulus measurements, the nanoindentation method allows also controlled experiments on the strain rate sensitivity, which are discussed in detail in this paper. Nanoindentation measurements can be performed at indentation strain rates between 10-3 s-1 and 0.1 s-1. Nanocrystalline and ultrafine-grained fcc metals as Al and Ni show a significant strain rate sensitivity at room temperature in comparison with conventional grain sized materials. In ultrafine-grained bcc Fe the strain rate sensitivity does not change significantly after severe plastic deformation. Inelastic effects are found during repeated unloading-loading experiments in nanoindentations.

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