Synthesis of Fe–Al–Si intermediary phases by reactive sintering

Abstract

In this work, Fe-Al-Si alloys were prepared by reactive sintering. The contents of silicon and aluminium ranged between 0-30 wt-% and 10-40 wt-% respectively. Aluminium, silicon and AlSi30 master alloy powders prepared by mechanical machining and/or milling and commercial powder of high purity iron were used for sintering. Powders were blended and pressed at room temperature. Sintering was carried out at 950uC for 60 min. Compact low porosity products without unreacted components were prepared, if a powder mixture contained 15-20 wt-% of silicon and 20-25 wt-% of aluminium. It was shown that these materials contain two phases (Al 2 FeSi and AlFeSi). Hardness of the alloys increased with growing silicon content, while the increase in aluminium content reduced the hardness.

On the formation of intermetallics in Fe–Al system – An in situ XRD study

“…is fully transformed to FeAl phase. For this reason, nearly pure FeAl phase was observed after reactive sintering in our previous work [7].…”

“…However, low room-temperature ductility and problematic production of these materials by conventional melting processes limit their applicability up to current days. There were many attempts to overcome the above mentioned limitations [2e5], while one of them is the powder metallurgy using reactive sintering [6,7]. In this process, intermetallics are produced by thermally-activated in situ reactions during sintering of compressed elemental powder mixtures.…”

Structure and Properties of Fe-Ni-Al-Si Alloys Produced by Powder Metallurgy

“…In addition, silicon forms an eutectic with aluminium which melts at lower temperature than aluminium (577 • C). Therefore the time of the melt existence during heating prior the formation of intermetallics is prolonged [8]. Due to this fact, melt is able to ll the pores between iron particles.…”

“…Optimum alloy composition was previously determined as FeAl20Si20 (given in wt%) [8]. In this work, the effect of partial replacement of iron by nickel, as a known aluminide-forming element, on the structure and properties of FeAlSi alloys was studied.…”

“…In our previous work, silicon was found to reduce the porosity of FeAl alloys produced by reactive sintering [8,9]. Silicon added to FeAl alloys completely modies the intermetallic phases' formation mechanism.…”