P. Z. Shen

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.

Mechanical properties of porous Fe–Al intermetallics

Abstract The effects of Al content and porosity on the mechanical properties of porous Fe–Al intermetallics, particularly at high temperatures, were determined using scanning electron microscopy, X-ray diffraction and mechanical properties testing. Results show that the optimal mechanical properties are achieved at 20 to 30 wt-%Al content. The tensile and bend strengths decrease with increasing Al content at 35 to 60 wt-%Al content. The quantitative relationship between porosity and strength for porous Fe–Al intermetallics can be described as σb = 181(1−θ)3.3. The strength of porous Fe–Al intermetallics increases at medium temperature with the increase in temperature from room temperature. The maximum tensile strength (50.2 MPa) is achieved at 600°C, which is almost 36.8% higher than that at room temperature.

Congenerous and heterogeneous brazing of porous FeAl intermetallics

Abstract Congenerous and heterogeneous brazing of porous FeAl intermetallics has been successfully realised using Cu–10Sn green compact as brazing filler. Cu–Sn intermetallic phases combined with (Cu,Sn) solid solution were formed in the brazing line for congenerous brazing, while (Cu,Sn) solid solution was the main phase formed for heterogeneous brazing. Maximum tensile strengths for congenerous and heterogeneous brazing are 75·0 and 83·9 MPa which are about 81·5 and 91·2% of that of porous FeAl alloy (∼92·0 Mpa) respectively. The interface structure of the stainless steel and porous FeAl joint brazed at 940°C for 15 min is S–S+(Cu,Sn)/(Cu,Sn)/Cu9Al4+(Cu,Fe)+(Cu,Sn)/AlFe3+Al4Cu9+(Cu,Sn). In the porous FeAl and porous FeAl joint brazed with Cu–10Sn filler at 940°C, Cu–Sn intermetallics and (Cu,Sn) solid solution were the main phases in the joint line.