Hostname: page-component-7bb8b95d7b-wpx69 Total loading time: 0 Render date: 2024-09-11T23:47:24.278Z Has data issue: false hasContentIssue false

The Strengthening Mechanism in Consolidated Rapidly Solidified Alloys

Published online by Cambridge University Press:  25 February 2011

Monde A. Otooni*
Affiliation:
U.S. Army Research Office, Physics Division, Research Triangle Park, NC 27709-2211
Get access

Abstract

Attempts have been made to study mechanisms of strengthening in the Ni68W22C8B2 and the Ni45CO20 Cr10MO4Fe5B16 alloy systems during their amorphous crysialline transitions. In the Ni68W22C8B2 system where amorphous particulates of varying sizes have been cons Ti a ed at high pressure and low temperature (3.6 MPa, and 673°K respectively), the initial stage of crystallization is marked by transformation of the localized regions of the specimen. These crystallized regions contain microcracks and voids. Microhardness measurements from the consolidated specimens indicate an increasing trend in the microhardness with decreasing particulate sizes. Premature failures of the consolidated specimen during tensile stress measurements have been attributed to the presence of microcracks and voids in these specimens. In the Ni45Co20Crl0Mo4Fe5B16 alloy system isothermal annealing of an initially amorphous alloy has been allowed to produce grains of varying sizes. The tensile stress measurements from these thermally annealed ribbons indicate two distinctly different functional relationships between the strength, σ, and the grain size parameter, λ. In the early stage of transformation where grain reach a maximum growth of up to 400 Å, the functional form of the strength, σ, with the grain parameter, λ, is σ = σ + K Log λ, where σO and K are constants. During latter stages of transformation, where grains larger than 400 Å have been formed, the strength, σ, varies with the inverse square root of the grain sizes. This latter relationship is analogous with the well known Hall-Petch relationships, which describes the strength, σ, as a function of the grain sizes in conventionally processed alloys.

Type
Research Article
Copyright
Copyright © Materials Research Society 1986

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1.Miller, S. A. and Murphy, R. J., “The Kinetics of Consolidation of Amorphous Cu60-Zr40 Powder by Warm Processing, Proc. 4th Int. Conf. on Rapidly Quiched Materials. Vol. I, (SENDAI), 1981, pp. 137140.Google Scholar
2.Jolly, M. R. and Honeycombe, R. W. K., “The Properties and Microstructures of Compacted Melt Spun Tin and Tin Based Alloys”, Proc. 4th Int. Conf. on Rapidly Quenched Materials, Vol. I, (SENDAI), 1981, pp. 133136.Google Scholar
3.Otooni, M. A., “Kinetics of Crystallization in the Cu60-Zr40 Alloy System”, Journal Noncryst.Solids, 65, pp. 389402, (1984).Google Scholar
4.Otooni, M. A., “Laser Anneal and the Onset of Amorphous Crystalline Transition in the Amorphous Cu60-Zr40 Alloy System”, Proc. of Mat. Res. Conf., Nov. 1983.Google Scholar
5.Clauer, A. H., et. al., “Consolidated Studies of Metallic Glass Strips and Microcrystalline Strips and Particulates”, from “Amorphous Glassy Metals and Microcrystalline Applications”, AFML-TR-78-80, pp. 399402, Battelle Columbus Laboratories, 1980.Google Scholar
6.Otooni, M. A., “Strengthening Mechanism in the Consolidated Rapidly Solidified Alloy”, Tech Report ARSCD-TR-84017, pp. 215, 1984.Google Scholar
7.Piller, J. and Haasen, P., Acta Met, 1, pp. 3035, (1982).Google Scholar