Fe3Al Matrix Research Articles

Properties of Fe 3Al matrix composites with Al 2O 3 particle dispersions

Fe 3Al matrix composites reinforced with 0–13 vol.% fine alumina particles were fabricated by hot pressing powder mixtures of iron and aluminium. The microstructure and mechanical and several other properties of the alumina-reinforced composites were examined. As a result of the dispersion of alumina powder, the grain size of the matrix decreased. No third phase was observed between the matrix and the alumina by transmission electron microscopy. The matrix alloy showed quite good tensile strength (above 800 MPa) as well as good elongation (up to 5%) at room temperature. On increasing the volume fraction of alumina, the tensile strength increased slightly. The 0.2% proof stress was improved considerably more than the tensile strength and reached its maximum value at an alumina volume fraction of 2.5%. At 500 °C the strength of the composite was higher by 100 MPa than that of the monolithic alloy. The oxidation resistance of the Fe 3Al and its composites up to 1000°C proved to be quite good.

Synthesis of iron aluminide matrix in situ composites from elemental powders by reactive low pressure plasma spraying

A premixture of elemental powders of iron and aluminium was supplied as a spray material to synthesize iron aluminide matrix in situ composites by means of reactive low pressure plasma spraying (RLPPS). The aluminium content was varied from 13.9 to 59.2 mass% in the premixtures. Intermetallic matrix composites (IMCs) with a predominant FeAl matrix and exclusive in situ nitride of AlN are synthesized by RLPPS, which is performed using an Fe-32.6mass%Al premixture. AlN formation is better in RLPPS with a premixture as a spray material compared with RLPPS using an expensive FeAl intermetallic powder. Although AlN is an exclusive in situ nitride, the matrix constituents vary with the different aluminium contents in the premixtures. Increasing the aluminium content leads to a change in the iron aluminides from FeAl to FeAl 2 and Fe 2Al 5 as the matrix. The iron aluminide with predominantly Fe 2Al 5 matrix composite showed the highest hardness of over 700 Hv at room temperature. However, the partial decomposition of the in situ nitride AlN occurred through annealing at 1173 K for 86.4 ks in vacuum. The microhardness of sprayed IMCs after the annealing decreases, because of the partial decomposition of AlN. RLPPS could be one of the characteristic fabrication methods of iron aluminide matrix in situ composites which are expected to be an advanced material in wear-resistance applications at medium temperatures.