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Crystallization Behavior and Properties of Rapidly Solidified Ni-Mo-B Alloys

Published online by Cambridge University Press:  15 February 2011

C.C. Wan*
Affiliation:
AiResearch Casting Company, Torrance, CA *
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Abstract

The crystallization phenomena of certain ternary glass Ni-Mo-B alloys and their consolidated bulk properties, including age hardening effects after proper heat treatment, are investigated. Within the composition range studied, the glassy alloys crystallize by a two-stage process - first by forming a metastable microcrystalline structure of Ni solid solution at temperature around 490–530°C followed by boride precipitation at temperatures around 700–770°C. The boride, which is identified by x-ray diffraction as Mo2NiB2 , grows to submicron size after the alloys have been thermally treated at 1000°C and above for certain periods of time. Microstructural analysis shows borides isolated and well dispersed in Ni-Mo alloy matrix. Age hardening is achieved by precipitating the Ni/Mo intermetallic compound(s) in Ni-Mo matrix at an intermediate temperature of previously solutionized samples. Another characteristic of this group of alloys is the relatively high eutectic temperature, i.e. 1230°C and above. This will allow the alloys to be hot consolidated to full density by certain commercially available processes, such as hot isostatic pressing (HIP), while still maintaining the unique microstructure inherited from rapid solidification process. Hardness, hot hardness and hot tensile properties of some consolidated alloys are discussed.

Type
Research Article
Copyright
Copyright © Materials Research Society 1982

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Footnotes

*

This work was conducted at Allied Corporation, Morristown, NJ, U.S.A.

References

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