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Physical and Mechanical Properties of Single Crystals of Co-Al-W Based Alloys with L12 Single-Phase and L12/fcc Two-Phase Microstructures

Published online by Cambridge University Press:  24 October 2018

Haruyuki Inui
Affiliation:
Department of Materials Science and Engineering, Kyoto University Sakyo-ku, Kyoto 606-8501, Japan
Katsushi Tanaka
Affiliation:
Department of Materials Science and Engineering, Kyoto University Sakyo-ku, Kyoto 606-8501, Japan
Kyosuke Kishida
Affiliation:
Department of Materials Science and Engineering, Kyoto University Sakyo-ku, Kyoto 606-8501, Japan
Norihiko L. Okamoto
Affiliation:
Department of Materials Science and Engineering, Kyoto University Sakyo-ku, Kyoto 606-8501, Japan
Takashi Oohashi
Affiliation:
Department of Materials Science and Engineering, Kyoto University Sakyo-ku, Kyoto 606-8501, Japan
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Abstract

Single-crystal elastic constants of Co3(Al,W) with the cubic L12 structure have been experimentally measured by resonance ultrasound spectroscopy at liquid helium temperature. The values of all the three independent single-crystal elastic constants and polycrystalline elastic constants of Co3(Al,W) experimentally determined are 15~25% larger than those of Ni3(Al,Ta) but are considerably smaller than those previously reported. Two-phase microstructures with cuboidal L12 precipitates being well aligned parallel to <100> and well faceted parallel to {100} are expected to form very easily in Co-base superalloys because of the large value of E111/E100 and cij of Co3(Al,W). This is indeed confirmed by experiment. Values of yield stress obtained for both [001] and [¯123] orientations of L12/fcc two-phase single crystals moderately decrease with the increase in temperature up to 800°C and then decrease rapidly with temperature above 800°C without any anomaly in yield stress. Slip on {111} is observed to occur for both orientations in the whole temperature range investigated.

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Articles
Copyright
Copyright © Materials Research Society 2009

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