철계 반비정질 합금 분말과 VC 분말을 고에너지 전자빔으로 투사하여 제조된 표면복합재료의 미세조직, 경도, 파괴인성 (Microstructure, Hardness, and Fracture Toughness of Surface Composites Fabricated by High-Energy Electron-Beam Irradiation of Fe-Based Metamorphic Alloy Powders and VC Powders)

서지정보

· 발행기관 : 대한금속·재료학회
· 수록지 정보 : 대한금속·재료학회지 / 46권 / 10호 / 634 ~ 645페이지
· 저자명 : 남덕현, 도정현, 이성학

초록

In this study, surface composites were fabricated with Fe-based amorphous alloy powders and VC
powders by high-energy electron beam irradiation, and the correlation of their microstructure with hardness
and fracture toughness was investigated. Mixture of Fe-based metamorphic powders and VC powders were
deposited on a plain carbon steel substrate, and then electron beam was irradiated on these powders without
flux to fabricate surface composites. The composite layers of 1.3~1.8 mm in thickness were homogeneously
formed without defects and contained a large amount (up to 47 vol.%) of hard Cr2B and V8C7 crystalline
particles precipitated in the solidification cell region and austenite matrix, respectively. The hardness of the
surface composites was directly influenced by hard Cr2B and V8C7 particles, and thus was about 2 to 4 times
greater than that of the steel substrate. Observation of the microfracture process and measurement of fracture
toughness of the surface composites indicated that the fracture toughness increased with increasing additional
volume fraction of V8C7 particles because V8C7 particles effectively played a role in blocking the crack
propagation along the solidification cell region heavily populated with Cr2B particles. Particularly in the surface
composite fabricated with Fe-based metamorphic powders and 30 % of VC powders, the hardness and fracture
toughness were twice higher than those of the surface composite fabricated without mixing of VC powders.

영어초록

In this study, surface composites were fabricated with Fe-based amorphous alloy powders and VC
powders by high-energy electron beam irradiation, and the correlation of their microstructure with hardness
and fracture toughness was investigated. Mixture of Fe-based metamorphic powders and VC powders were
deposited on a plain carbon steel substrate, and then electron beam was irradiated on these powders without
flux to fabricate surface composites. The composite layers of 1.3~1.8 mm in thickness were homogeneously
formed without defects and contained a large amount (up to 47 vol.%) of hard Cr2B and V8C7 crystalline
particles precipitated in the solidification cell region and austenite matrix, respectively. The hardness of the
surface composites was directly influenced by hard Cr2B and V8C7 particles, and thus was about 2 to 4 times
greater than that of the steel substrate. Observation of the microfracture process and measurement of fracture
toughness of the surface composites indicated that the fracture toughness increased with increasing additional
volume fraction of V8C7 particles because V8C7 particles effectively played a role in blocking the crack
propagation along the solidification cell region heavily populated with Cr2B particles. Particularly in the surface
composite fabricated with Fe-based metamorphic powders and 30 % of VC powders, the hardness and fracture
toughness were twice higher than those of the surface composite fabricated without mixing of VC powders.

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