M{umlt o}ssbauer investigation of intermixing during ball milling of Fe{sub 0.3}Cr{sub 0.7} and Fe{sub 0.5}W{sub 0.5} powder mixtures
- Laboratoire de Science et Genie des Materiaux Metalliques, associe au C.N.R.S. U.R.A. 159, Ecole des Mines, F-54042 Nancy Cedex (France)
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695-7907 (United States)
- Laboratoire de Chimie du Solide Mineral, associe au C.N.R.S. U.R.A. 158, Universite Henri Poincare, Boite Postale 239, F-54506 Vandoeuvre-les-Nancy Cedex (France)
Intermixing of Fe and T (T=Cr,W) during ball milling of elemental powder mixtures Fe{sub 1{minus}x}T{sub x}, with x=0.70 for T=Cr and x=0.50 for T=W, has been followed by {sup 57}Fe M{umlt o}ssbauer spectroscopy at room temperature (RT) and by magnetization measurements for T=W. The chemical compositions have been chosen to yield final alloys or compounds which are nonmagnetic at RT to better follow the evolution of magnetic phases with milling times. For a long period of milling time t{sub m} before reaching the final stationary state, the hyperfine magnetic field distributions remain stationary in shape for both T=Cr and T=W. Only the relative weight of the magnetic contribution decreases with t{sub m}. For T=W, the average moment of magnetic Fe atoms is further shown to remain constant with t{sub m}. Stationary hyperfine field distribution shapes are found to be similar not only for {ital T}=Cr and W but also for T=Si (x=0.50) while published spectra suggest to add T=Al, Ti, V, Ta, Re to the latter nonexhaustive list. The stationary shape is characterized by a narrow peak located at a field close to the field of alpha iron at RT (330 kG) and by a broad, almost featureless, band from 50-100 kG to 300-320 kG. The broad band represents about 2/3 of the normalized field distribution. We deduce that the interpretation which consists in attributing the x-ray diffraction peaks of Fe-based bcc solid solutions to a single Fe-rich homogeneous solid solution must be done with care for intermediate milling times. We cannot infer from such hyperfine measurements a detailed description of the regions of the powders which are responsible for such magnetic features. We argue however that irregular interfaces between nanometer-sized Fe-rich zones and {ital T}-rich zones may play a role to explain the observed shape of the hyperfine field distributions.
- OSTI ID:
- 392672
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 54, Issue 18; Other Information: PBD: Nov 1996
- Country of Publication:
- United States
- Language:
- English
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