Abstract
In a previous paper (J. Japan Inst. Metals, 26 (1962), 348), the-effect of a brittle phase surrounding ductile phase on the yield strength was investigated and the following formula was obtained:
(σ_s - σ_0)^2 = K [{(γ_1 - γ_2)/d}f + γ_2/d:] Where σs is the yield strength, σ0 is the back stress of dislocations, d is the diameter of ductile phase γ1 and γ2 are respectively measures of the strength of ductile/brittle phase boundary and ductile/ductile phase boundary, f is the length fraction of brittle phase boundary and K is the constant.
In copper-aluminium alloy, the ratio γ1 to γ2 in the case of yielding was obtained as follows: (γ_1/γ_2)_yield \simeq2
In the present paper, the relationship between the fatigue strength and the structure was examined using the alloys which were treated under the same conditions as previously reported. The experimental results also satisfied the above mentioned formula in the fatigue strength, and the ratio γ1′ to γ2′ in the case of fatigue rupture was similarily obtained as follows: (γ_1’/γ_2’)_fatigue \simeq2
