日本金属学会誌

J. Japan Inst. Metals, Vol. 40, No. 2 (1976),
pp. 167-174

Effect of Diffusion-annealing on the Deformation Behavior of Aluminium Single Crystals Coated with Zinc, Silver, and Copper Films

Takayuki Takasugi1 and Osamu Izumi1

1The Research Institute for Iron, Steel and Other Metals, Tohoku University, Sendai

Abstract:

The effects of diffusion-annealing on the deformation of aluminium single crystals coated with Zn, Ag, and Cu films were studied by the tensile test, X-ray analysis and surface marking observation. After annealing, the Zn-coated specimens consist of a solid solution phase, while the Ag- and Cu-coated specimens consist of intermetallic compound phases at the surface layers.
In the former specimens, the following results are obtained:
(1) The yield stress of the specimens diffusion-annealed at 375°C initially decreases abruptly, then gradually approaches the yield stress of the uncoated specimen as the diffusion-annealing time increases.
(2) The yield stresses of the diffusion-annealed specimens are closely related to the concentration distributions at the surface layers which cause an image force effect against moving dislocations.
In the latter specimens, the following results are summarized.
(1) By diffusion-annealing at 530°C, both the specimens coated with 2.0 μ Cu and Ag show marked increases in yield and flow stresses. The degree of such a strengthening is higher in the former than in the latter. A longer diffusion-annealing induces the breakdown in the strength.
(2) It is concluded that the surface strengthening by diffusion-annealing in these specimens is caused by the formation of intermetallic compounds at the surface layer. Such a intermetallic compound layer seems to act as the resistance to deformation.


(Received 1975/07/26)

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