Glass transition and crystallization of Al–Ni–La based metallic glasses studied by temperature modulated DSC

Crystallization behavior and glass transition phenomenon of Al89Ni6La5, Al87Ni6La7 and Al87Ni5La7M1 (M = Ag, Cu) metallic glasses have been studied by temperature modulated differential scanning calorimetry (TMDSC). A clear glass transition of these glasses, which could not be detected in conventional differential scanning calorimetry (DSC), even at higher heating rates, was observed through TMDSC measurements. All these glasses undergo two-stages of crystallization on heating. The precipitation and growth of fcc-Al in Al89Ni6La5 and bcc-metastable phase in other alloys are responsible for the first stage of crystallization. The glass transition phenomenon in these alloys except Al87Ni6La7, could not be detected in DSC because the signals are overlapped with the relatively large heat release from the primary crystallization. This was confirmed from the TMDSC measurements. These measurements were necessary for the development of new nanocrystalline/amorphous composite materials.

► Glass formability in Al-based alloys decreases with Ag or Cu addition.
► In TMDSC measurement Tg is clearly observed.
► TMDSC can separate reversible and non-reversible heat flow from total heat flow.