MATERIALS TRANSACTIONS
Online ISSN : 1347-5320
Print ISSN : 1345-9678
ISSN-L : 1345-9678
Effect of Microstructural Continuity on Room-Temperature Fracture Toughness of ZrC-Added Mo–Si–B Alloys
Shunichi NakayamaNobuaki SekidoSojiro UemuraSadahiro TsurekawaKyosuke Yoshimi
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2018 Volume 59 Issue 4 Pages 518-527

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Abstract

The room-temperature fracture toughness of ZrC-added Mo–Si–B alloys prepared using an arc-melting technique was investigated. The constituent phases of the heat-treated alloys were mainly molybdenum solid solution (Moss), Mo5SiB2 (T2), and ZrC, with a small amount of Mo2B in a few alloys. Four-point bending tests with a Chevron-notch were performed, and the average fracture-toughness values ranged from 12.4 to 20.3 MPa(m)1/2 depending on alloy composition. Here, the effects of the volume fractions of the constituent phases and the continuity of Moss on the fracture toughness are discussed. The fracture toughness improved with an increase in the volume fractions of the Moss and ZrC phases. Alloys with a higher Moss continuity exhibited higher fracture toughness, for example, the fracture toughness of 64.5Mo–3.2Si–6.5B–12.9Zr–12.9C (mol.%) was 19 MPa(m)1/2; the alloy contained a >95%-continuous Moss phase, even though it also contained 16 vol.% T2 and 23 vol.% ZrC.

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© 2018 The Japan Institute of Metals and Materials
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