B.Y. Huang

Effect of heating rate on pore structure of porous FeAl material

Abstract The sintering behaviour of elemental powders of Fe and Al was investigated at various heating rates (0˙5–10°C min–1). It was found that the formation of porous FeAl material was accompanied by the volume expansion during the formation of the intermediate phase Fe2Al5. The final pore structure of porous FeAl material depends strongly on the heating rate; the higher the heating rate, the higher the volume expansion and the larger the porosity and the maximum pore size. It has been found that the pore structures produced with different heating rates experienced different formation routes.

Effects of Al content on porous Fe–Al alloys

Abstract Porous Fe–Al alloys with the nominal composition ranging from Fe–20 wt-%Al to Fe–60 wt-%Al have been fabricated by Fe and Al elemental powder reactive synthesis. The effects of the Al content on the pore properties of resultant porous Fe–Al alloys were systematically studied. It has been found that the volume expansion, the open porosity and the permeability can be manipulated by varying the Al content and that their maximum values are reached at Fe–45 wt-%Al. Their mechanical properties suggest that they are strong enough for the filtration applications.

Criterion to control self-propagation high temperature synthesis for porous Ti–Al intermetallics

Abstract The criterion to control self-propagation high temperature synthesis for the fabrication of porous Ti–Al intermetallics was established from the prereaction model and the thermal balance condition. The criterion equation reflecting the relation between the solid reaction layer thickness correlation parameter and the ignition temperature was deduced to be p3 = C1/(Tad−T0)+C2, according to which the near net shaping synthesis of porous Ti–Al intermetallics was realised, which was significantly important for the industrial productions and applications of this high performance novel porous material. The slight difference between theoretical predictions and experimental data was analysed according to the model analysis.

Comparative assessment of microstructure and compressive behaviours of PM TiAl alloy prepared by HIP and pseudo‐HIP technology

Abstract The present work discusses conditions of comparable microstructure and compressive behaviours of powder metallurgy (PM) Ti–46Al–(Cr,Nb,W,B) (at.‐%) alloy prepared by hot isostatic pressing (HIP) and pseudo‐HIP technology respectively. A PM route based on pseudo‐HIP of alloy powder prepared by plasma rotating electrode process was used for the rapid fabrication of high quality TiAl alloys. The pseudo‐hipped alloy shows a fine grained microstructure which is significantly finer than that of the hipped alloy consolidated under similar conditions. The pseudo‐hipped alloy exhibits more excellent compression properties than that of the hipped alloy at elevated temperatures. By using the kinetic rate equation, the stress exponent n and the apparent activation energy Q are determined and discussed respectively. The influence of microstructure on the flow behaviour during the total hot compressive deformation was studied. The role of submicrocrystalline forming and dynamic recrystallisation due to mechanical twinning and grain matrix deformation will be discussed.