Low temperature dislocation mechanisms in ordered and disordered Cu3Au

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Abstract
The temperature and strain rate dependence of the flow stress of ordered and disordered polycrystalline Cu3Au was investigated in the range 20°–420°K. A thermally activated deformation mechanism was observed at temperatures less than ∼100°K and ∼340°K for the ordered and disordered material respectively. For ordered Cu3Au, the experimental data were shown to correlate well with the requirements of the Peierls mechanism over the entire thermally activated region; for the disordered material, good agreement was only obtained at temperatures less than ∼120°K, and it appeared that deformation was by the intersection mechanism in the temperature range ∼220°–340°K. It is suggested that a pseudo-Peierls mechanism occurs in ordered Cu3Au at temperatures less than ∼100°K, and in disordered Cu3Au at temperatures less than ∼120°K, due to splitting of the cores of screw dislocations on several planes.