The effects of concentration of solute atoms, cold working, and low temperature annealing on the macro yield point (spring limit or ``Federungsgrenze'') of α-copper alloys (Cu-Zn, Cu-Al, Cu-Ni-Zn, Cu-Sn-P alloys) were investigated. The results were as follows: (1) The spring limit of the rolled specimen initially increases with the degree of cold work, and finally reaches a saturation value. (2) After low temperature annealing, however, the spring limit of the specimen rises remarkably and increases continuously with the increasing pre-cold-rolling and with the concentration of solute atoms. (3) This increase of spring limit by low temperature annealing depends upon the density of valence electrons and seems to be not dependent upon the kinds of solute atoms as shown in Fig. 8. This phenomenon is explained qualitatively by the theory of chemical interaction between dislocations and solute atoms proposed by H. Suzuki.
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