日本金属学会誌

J. Japan Inst. Metals, Vol. 32, No. 4 (1968),
pp. 385-390

Strain Rate and Temperature Dependence of the Flow Stress of Copper-Manganese Dilute Alloy Single Crystals

Norio Nagata1 and Susumu Yoshida1

1National Research Institute for Metals, Tokyo

Abstract:

The strain rate and temperature dependence of the flow stress of copper (99.99% purity) and copper-manganese (0.1∼1.1 wt%) dilute alloy single crystals with the orientations suitable for easy glide has been investigated by compression tests over the strain rate range of 10-4 to 103 sec-1 and the temperature range of 77°K to 373°K.
The critical resolved shear stress (CRSS) at room temperature gradually increases with increasing strain rate over the low strain rate range, but rapidly increases over the high strain rate range. At low strain rates the CRSS increases with decreasing temperature and increases nearly in proportion to the atomic concentration of manganese. On the contrary, at high strain rates the CRSS for pure copper and 0.1%Mn alloy scarcely varies with temperature, but rather tends to increase with increasing temperature. However, for 0.5% and 1.1%Mn alloys it decreases with increasing temperature. The manganese concentration dependence of the CRSS at low strain rates and its temperature dependence at low temperatures are well explained by Friedel's solid solution hardening theory. The temperature dependence for 0.5% and 1.1%Mn alloys at high strain rates is also explained qualitatively by the same theory. It is considered that the strain rate dependence in the low strain rate range is controlled by the non-conservative motion of jogs on moving dislocations. On the contrary, for the explanation of the magnitude and the strain rate dependence of the CRSS for pure copper and 0.1%Mn alloy in the high strain rate range, the frictional resistance against moving dislocations from the crystal lattice should be taken into consideration. It is also presumed that the frictional resistance contributes considerably to the deformation of 0.5% and 1.1%Mn alloys crystals at high strain rates.


(Received 1967/11/10)

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