Nanocrystalline Formation during Mechanical Attrition of Cobalt

Abstract:

The nanocrystalline (nc) formation was studied in cobalt (a mixture of ε (hexagonal close packed) and γ (face-centered cubic) phases) subjected to surface mechanical attrition treatment. Electron microscopy revealed the operation of { 10 10 }〈 1120 〉 prismatic and {0001}〈 1120 〉 basal slip in the ε phase, leading to the successive subdivision of grains to nanoscale. In particular, the dislocation splitting into the stacking faults was observed to occur in ultrafine and nc grains. By contrast, the planar dislocation arrays, twins and martensites were evidenced in the γ phase. The strain-induced γ→ε martensitic transformation was found to progress continuously in ultrafine and nc grains as the strain increased. The nc formation in the γ phase was interpreted in terms of the martensitic transformation and twinning.

• Periodical: Materials Science Forum (Volumes 503-504)
• Pages: 751-756
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.503-504.751
• Online since: January 2006
• Authors: J. Zhou, C. Sun, X. Wu, N.R. Tao, Gang Liu, X. Meng, You Shi Hong
• Keywords: Cobalt, Grain Refinement, Nanostructure, Surface Mechanical Attrition Treatment (SMAT)

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