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Occurrence of plastic instabilities in dynamic microhardness testing

Published online by Cambridge University Press:  31 January 2011

G. Bérces ,
N. Q. Chinh ,
A. Juháasz  and
J. Lendvai
G. Bérces
Affiliation:
Department of General Physics, Eötvös University, Budapest, H-1088 Múzeum krt. 6–8, Budapest, Hungary
N. Q. Chinh
Affiliation:
Department of General Physics, Eötvös University, Budapest, H-1088 Múzeum krt. 6–8, Budapest, Hungary
A. Juháasz
Affiliation:
Department of General Physics, Eötvös University, Budapest, H-1088 Múzeum krt. 6–8, Budapest, Hungary
J. Lendvai
Affiliation:
Department of General Physics, Eötvös University, Budapest, H-1088 Múzeum krt. 6–8, Budapest, Hungary
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Abstract

Plastic instabilities were observed to appear during dynamic ultramicrohardness testing of a solid solution Al–3.3 wt.% Mg alloy. The tests were carried out at room temperature with a Vickers hardness indenter in a computer-controlled dynamic ultramicrohardness testing machine. During the tests the applied load was increased from 0 to 2000 mN at constant loading rate. The instabilities appear as characteristic steps in the continuously recorded load-indentation depth curves. The physical basis for the occurrence of the instabilities is the interaction between moving dislocations and solute atoms, a phenomenon termed in the literature as serrated yielding, jerky flow, or Portevin-Le Châtelier effect. The instabilities start at a critical load, Fc, in the depth-load curve. Varying the loading rate, μ, by two orders of magnitude Fc was found to increase linearly with the loading rate.

Type
Articles
Information
Journal of Materials Research , Volume 13 , Issue 6 , June 1998 , pp. 1411 - 1413
Copyright
Copyright © Materials Research Society 1998

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References

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