Finely dispersed metal powders have been obtained after chemical reduction of Ni and Co acetylacetonate by lithium aluminum hydride in tetrahydrofuran at low temperature. The Al/Ni and Al/Co stoichiometry of the as-reduced powders was 1.1 and 1.2, respectively. The structure and thermal stability of the as-reduced powders were affected by the temperature of reduction. For the NiAl powders it was found that the thermal treatment initially induces a separation of highly unstable Ni(Al) and Al(Ni) solid solutions, which subsequently react to give a single NiAl phase of cubic structure not reported in the equilibrium phase diagram. Conversely, the reduction of cobalt acetylacetonate directly gives a cubic metastable phase, from which precipitates some hexagonal form of Co after treatment at 450-degrees-C.
STRUCTURAL STUDIES OF AL-BASED POWDERS PREPARED BY CHEMICAL METHODS / Lenarda, M; Ganzerla, R; Storaro, L; Frattini, R; Enzo, Stefano. - In: JOURNAL OF MATERIALS RESEARCH. - ISSN 0884-2914. - 7:9(1992), pp. 2418-2423. [10.1557/JMR.1992.2418]
STRUCTURAL STUDIES OF AL-BASED POWDERS PREPARED BY CHEMICAL METHODS
ENZO, Stefano
1992-01-01
Abstract
Finely dispersed metal powders have been obtained after chemical reduction of Ni and Co acetylacetonate by lithium aluminum hydride in tetrahydrofuran at low temperature. The Al/Ni and Al/Co stoichiometry of the as-reduced powders was 1.1 and 1.2, respectively. The structure and thermal stability of the as-reduced powders were affected by the temperature of reduction. For the NiAl powders it was found that the thermal treatment initially induces a separation of highly unstable Ni(Al) and Al(Ni) solid solutions, which subsequently react to give a single NiAl phase of cubic structure not reported in the equilibrium phase diagram. Conversely, the reduction of cobalt acetylacetonate directly gives a cubic metastable phase, from which precipitates some hexagonal form of Co after treatment at 450-degrees-C.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.