Structure and Elevated-temperature Strength of P/M Al-Fe-M-Ti(M=V, Cr, Mn)Alloys Containing Quasicrystalline Phase

Abstract

Powder metallurgy (P/M) alloys of Al-3 at%Fe-3 at%M-2 at%Ti (M=V, Cr, Mn) were prepared by extruding gas atomized powders with the sizes smaller than 75μm at 673 K. The constituent structure was quasicrystalline (Q.C.)+Al+Al₂₃Ti₉+Al₁₃Fe₄ for the M=V alloy, Q.C.+Al+Al₂₃Ti₉ for the M=Cr alloy and Q.C.+Al+Al₂₃Ti₉ for the M=Mn alloy. The Q.C. particles in the P/M Al-3 at%Fe-3 at%M-2 at%Ti (M=Cr, Mn) alloys have an icosahedral structure and their particle sizes are 300 to 900 run. The analysis by an energy dispersive x-ray spectrometer indicates that the compositions of Q.C. particles of the P/M Al-3 at%Fe-3 at%M-2 at%Ti (M=Cr, Mn) alloys are Al-6.1 at%Fe-6.8 at%Cr-2.4 at%Ti and Al-7.8 at%Fe-8.0 at%Mn-1.4 at%Ti, respectively. The volume fraction of the Q.C. particles decreases in the order of M=Cr>Mn>V in the P/M Al-3 at%Fe-3 at%M-2 at%Ti (M=V, Cr, Mn) alloys. The ultimate tensile strength (σ_urs), 0.2% proof strength (σ_0.2), plastic elongation (εp), Young's modules (E) and Vickers hardness (H_v) of the P/M Al-3 at%Fe-3 at%M-2 at%Ti (M=V, Cr, Mn) alloys are 494 MPa, 407 MPa, 5.5%, 87 GPa, 159 for the M=V alloy, 581 MPa, 488 MPa, 3.3 %, 85 GPa, 191 for the M=Cr alloy, 584 MPa, 491 MPa, 2.7%, 89 GPa, 191 for the M=Mn alloy, respectively, at room temperature. The σ_vrs, σ_0.2. and ε_p of the P/M Al-3 at%Fe-3 at%M-2 at%Ti (M=V, Cr, Mn) alloys are 250 MPa, 221 MPa and 8.9% for the M=V alloy, 302 MPa, 277 MPa and 5.6 % for the M=Cr alloy, and 238 MPa, 190 MPa, 8.8% for the M=Mn alloy, respectively, after holding for 100 h at 573K.