TY - GEN
T1 - Formation and alloying of elemental nanostructured β-W powders
AU - Angastiniotis, N. C.
AU - Kear, B. H.
AU - McCandlish, L. E.
AU - Ramanujachary, K. V.
AU - Greenblatt, M.
PY - 1992
Y1 - 1992
N2 - We have been investigating the reductive decomposition of spray dried ammonium metatungstate (AMT). Reduction of the pyrolysed powder in flowing hydrogen at T≥625°C creates a high surface area microcrystalline form of α-W, with bcc structure. Reduction at T≤575°C results in the formation of a high surface area nanocrystalline form of β-W, with A15 structure and chemical composition of W3O. The ideal A15 structure of W3O (isostructural with Nb3Sn) is a bcc lattice of oxygen atoms with tungsten atoms arranged in pairs on cube faces. In situ reduction experiments carried out in a controlled atmosphere, high temperature X-ray powder diffractometer have shown that W3O transforms to elemental β-W, in which all or nearly all of the oxygen atoms are absent. Various experiments confirming the existence of metastable elemental β-W are described. Initial experiments on its alloying behavior are also discussed.
AB - We have been investigating the reductive decomposition of spray dried ammonium metatungstate (AMT). Reduction of the pyrolysed powder in flowing hydrogen at T≥625°C creates a high surface area microcrystalline form of α-W, with bcc structure. Reduction at T≤575°C results in the formation of a high surface area nanocrystalline form of β-W, with A15 structure and chemical composition of W3O. The ideal A15 structure of W3O (isostructural with Nb3Sn) is a bcc lattice of oxygen atoms with tungsten atoms arranged in pairs on cube faces. In situ reduction experiments carried out in a controlled atmosphere, high temperature X-ray powder diffractometer have shown that W3O transforms to elemental β-W, in which all or nearly all of the oxygen atoms are absent. Various experiments confirming the existence of metastable elemental β-W are described. Initial experiments on its alloying behavior are also discussed.
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M3 - Conference contribution
AN - SCOPUS:0026992483
SN - 1878954261
T3 - Advances in Powder Metallurgy
SP - 29
EP - 39
BT - Novel Powder Processing
PB - Publ by Metal Powder Industries Federation
T2 - Proceedings of the 1992 Powder Metallurgy World Congress. Part 1 (of 9)
Y2 - 21 June 1992 through 26 June 1992
ER -