Studies on the Yield Strength of Dispersion Strengthened Alloys

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The present work deals with the yield strength and its temperature dependence of the dispersion strengthened alloy. Considering the interaction between a dislocation and the elastic stress field surrounding particle's due to the difference in thermal contraction between the matrix and the dispersed particle, the influence of the elastic stress field on the yield stress of the alloy was estimated. The yield stress of the alloy is shown approximately as γ_y=Gb/(λ+2d-2X)+γ_0, where G is the rigidity of the matrix, b is Burger's vector, λ is the interparticle spacing, d is the radius of the particle, γ_0 is the yield stress of the matrix metal and X which is an unknown factor relating to the distance of penetration of a dislocation into the stress field is given from this equation. b/(λ+2d-2X)=5.5〓a・〓t・d^3・sin(tan^<-1> d√<2>X)/(X^2+d^2/2)^<3/2>, where 〓_a is the difference in the coefficient of thermal expansion between the matrix and particle, and 〓t is defined by 〓t=T_A-T, where T is the testing temperature and T_A is the temperature for the initiation of stress when the alloy is cooled from a high temperature. These equations satisfy fairly well the experimental values of yield stresses for Fe-Al_2O_3, Fe-SiO_2, Ag-Al_2O_3 and other alloys.
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