TITLE:
Ball Milling and Annealing of Co-50 at% W Powders
AUTHORS:
A. S. Bolokang, M. J. Phasha, D. E. Motaung
KEYWORDS:
Ball Milling; Crystal Structure; XRD, Annealing; Co-W Powder
JOURNAL NAME:
International Journal of Nonferrous Metallurgy,
Vol.2 No.2,
April
22,
2013
ABSTRACT: Broadening and height reduction of X-ray diffraction peaks were observed after cold-pressing of unmilled Co-W powder mixture. It seems the effect of cold pressing has slightly reduced the lattice parameter of W from 3.165 to 3.143?. Consequent annealing of unmilled compacts yielded metastable phases. Upon 10 and 20 h ball milling of Co-W powder, no alloying was obtained. Although milling did not yield significant crystal changes in W and Co ground state structures, its effect is evident during subsequent annealing. An eta phase is obtained for the first time from unmilled-annealed Co-W powder mixture in the absence of interstitial elements like carbon, while the milled counterpart yielded the rhombohedral Co7W6-type phase with composition deviated from stoichiometric value.