Modification of the reactive synthesis of porous FeAl with addition of Si

Abstract

Porous Fe25Al–xSi intermetallics with various contents of Si were fabricated via reactive synthesis using Fe + Al + Si powder mixtures, in which the elemental Si was added to control the self-propagating High-temperature Synthesis (SHS) occurred during sintering process. The Si element added in Fe25Al could make the exothermic reactions in the synthesis process become mild and the total heat release from the system decrease. With increasing Si content from 0 to 5 wt-%, the open porosity, the maximum pore size and permeability increased from 38·14 to 50·12%, 27·9 to 35·7 μm and 5·13 × 10⁻¹² m² to 11·9 × 10⁻¹² m², respectively. Si element could affect the microstructure and phase evolution during the middle temperature sintering. Scattered τ₁ ((AlSi)₅Fe₃) phase surrounded Fe₂Al₅ layer transformed into loop-shape with increasing Si content. Fe(Al_1−x Si _x )₃ and Al₃FeSi phases substitute Fe₂Al₅ phase as the main intermediary phase when the Si content is beyond 3 wt-%.

Keywords:

• Si
• reactive synthesis
• SHS
• porous material
• FeAl

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [grant numbers 51404301, 51774336].