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Article Dans Une Revue J.Phys. IV Année : 1993

Kinetic and morphologic study of the pack-aluminisation of a series of refractory alloys

Daniel Claves
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Alain Galerie
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Résumé

Five refractory alloys, Fe-20Cr-20Ni, Fe-20Cr-36Ni, Fe-20Cr-45Ni, Fe-20Cr-60Ni and Ni-20Cr, were submitted to pack-aluminization at 850 °C for different durations in a NaF-activated pack. After a short period to achieve steady state, the coating kinetics were shown to be linear. The rate of aluminization was the same for the four alloys containing iron (about 1mg/cm2/h) and probably higher (1.8 mg/cm2/h) in the case of the Ni-20Cr alloy. The nature of the formed products and the morphology of the layers were shown to depend on the alloy composition. The most important feature was the presence of external FeAl3 on the four Fe-containing alloys, whereas a mixture of Ni2Al3 + NiAl was observed on the Ni-20Cr alloy. Kinetic experiments and thermodynamical calculations allowed a derivation of the value of the Al activity at the gas-substrate interface. The mechanisms involved in the aluminization were shown to depend on the Al concentration in the pack, on gaseous diffusion for low Al concentration and on interface reaction for high Al concentration.

Domaines

Chimie
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Dates et versions

hal-04051247 , version 1 (30-05-2023)

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  • HAL Id : hal-04051247 , version 1

Citer

Daniel Claves, Alain Galerie. Kinetic and morphologic study of the pack-aluminisation of a series of refractory alloys. J.Phys. IV, 1993, 3, pp.531-538. ⟨hal-04051247⟩
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