The mechanical treatment of a Al75Mo25mixture of pure elemental powders in a high-energy mixer mill induces partial solid state reactivity and solid solution formation. This is suggested by a quantitative phase evaluation and by the changes of Al lattice parameter carried out with Rietveld analysis of diffraction patterns collected after extended time of processing (4, 8, 16, 32, 57, and 78 h). The small angle neutron scattering experiments showed that diffusion processes are the rate-controlling step for these solid state reactions. The formation of metastable phases is confirmed byin situneutron diffraction annealing experiments on selected as-milled powders. In the specimen mechanically alloyed for 4 h, Al12Mo phase is formed at 590 °C (below the aluminum melting point). Soon after this temperature, the remaining Al is consumed to form the Al8Mo3phase. In the alloy mechanically treated for 32 h, the Al12Mo phase appears after annealing at 430 °C, while the Al8Mo3phase is found at 493 °C. After the disappearance of Al12Mo phase (500 °C), the solid state reaction proceeds to form a new tetragonal Al3Mo phase, not reported in the equilibrium phase diagram. In the specimen mechanically treated for 57 h, the total formation of Al8Mo3is recorded at 430 °C. Conversely, in the powder ball milled for 78 h, the Al8Mo3phase appears at 390 °C and coexists with tetragonal Al3Mo.

Neutron diffraction study of mechanically alloyed andin situannealed Al75Mo25powders / Enzo, Stefano; Canton, Patrizia; Delogu, Francesco; Monagheddu, Marzio; Frattini, Romana. - 87:6(2000), pp. 2753-2759. [10.1063/1.372251]

Neutron diffraction study of mechanically alloyed andin situannealed Al75Mo25powders

Enzo, Stefano;Delogu, Francesco;
2000-01-01

Abstract

The mechanical treatment of a Al75Mo25mixture of pure elemental powders in a high-energy mixer mill induces partial solid state reactivity and solid solution formation. This is suggested by a quantitative phase evaluation and by the changes of Al lattice parameter carried out with Rietveld analysis of diffraction patterns collected after extended time of processing (4, 8, 16, 32, 57, and 78 h). The small angle neutron scattering experiments showed that diffusion processes are the rate-controlling step for these solid state reactions. The formation of metastable phases is confirmed byin situneutron diffraction annealing experiments on selected as-milled powders. In the specimen mechanically alloyed for 4 h, Al12Mo phase is formed at 590 °C (below the aluminum melting point). Soon after this temperature, the remaining Al is consumed to form the Al8Mo3phase. In the alloy mechanically treated for 32 h, the Al12Mo phase appears after annealing at 430 °C, while the Al8Mo3phase is found at 493 °C. After the disappearance of Al12Mo phase (500 °C), the solid state reaction proceeds to form a new tetragonal Al3Mo phase, not reported in the equilibrium phase diagram. In the specimen mechanically treated for 57 h, the total formation of Al8Mo3is recorded at 430 °C. Conversely, in the powder ball milled for 78 h, the Al8Mo3phase appears at 390 °C and coexists with tetragonal Al3Mo.
2000
Neutron diffraction study of mechanically alloyed andin situannealed Al75Mo25powders / Enzo, Stefano; Canton, Patrizia; Delogu, Francesco; Monagheddu, Marzio; Frattini, Romana. - 87:6(2000), pp. 2753-2759. [10.1063/1.372251]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11388/262944
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