Effect of Grain Boundaries on PLC Plastic Instabilities

[+] Author and Article Information
Zs. Kovács, D. Fátay, K. Nyilas, J. Lendvai

Department of General Physics, Eötvös University, Budapest, H-1518, P.O.B. 32, Budapest, Hungary

J. Eng. Mater. Technol 124(1), 23-26 (May 30, 2001) (4 pages) doi:10.1115/1.1420195 History: Received March 20, 2001; Revised May 30, 2001
Copyright © 2002 by ASME
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Grahic Jump Location
Irregular small steps observed upon indentation near to the grain boundaries (lower curve) and a curve with regular instability steps obtained far away from grain boundaries. (The upper curve is shifted by 1 μm upwards.)
Grahic Jump Location
Large-step event on the indentation depth curve
Grahic Jump Location
(a) The penetration rate corresponding to the larger (•) and smaller (○) steps. The indentation curve can be divided into two distinct regular processes. (b) The load increase between subsequent steps in the two distinct processes.
Grahic Jump Location
The hardness of the large-step curve. The large-step corresponds to the large hardness drop. ΔHV and Δo show the preceding hardness increase and the overshooting, respectively, relative to the baseline curve, which corresponds to the normal (large-step free) case.
Grahic Jump Location
(a) The imprint near a triple junction and (b) the corresponding hardness load curve with two hardness drops
Grahic Jump Location
The ΔF(F) function for the large-step event. Deviation from the fitted linear can be seen only near the large-step event.
Grahic Jump Location
The result of the numerical simulation, where the steps in the strain indicate the PLC effect. The applied stress is also plotted. (a) Constant stress rate (b) constant stress rate with a stress rate pulse.



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