Mössbauer spectroscopy study of Ti–Zr–Ni–Fe icosahedral and approximant phases

Quaternary Ti53Zr21Ni13Fe13 alloys were prepared by melt-spinning using peripheral wheel speeds ω=19.5, 24.2 and 30 m/s. The icosahedral (i-) phase formation was studied using high resolution synchrotron radiation powder diffraction. An amorphous phase component is present irrespective of the rapid solidification conditions, its volume fraction decreasing towards lower quenching speed values. The amorphous phase coexists with a b.c.c. rational approximant phase (W-phase). For ω below 20 m/s the formation of an i-phase was also noticed. Transmission 57Fe Mössbauer spectroscopy measurements indicate that the number of asymmetrical Fe positions decreases with decreasing ω in agreement with the improved structural perfection of the W-phase and with the formation of an additional i-phase.