Rapidly solidified ribbons of Al90Nd7Ni3 metallic glasses were prepare d by using melt spinning. Crystallization process of the totally amorphous ribbo ns was investigated by differential scanning calorimetry and X-ra...Rapidly solidified ribbons of Al90Nd7Ni3 metallic glasses were prepare d by using melt spinning. Crystallization process of the totally amorphous ribbo ns was investigated by differential scanning calorimetry and X-ray diffraction analysis,under continuous heating regime. The results show that,under continuo us heating regime,the metallic glass devitrifies via two main stages: primary c rystallization,resulting in two-phase mixture of α（Al） plus residual amor phous phase,and secondary crystallization,corresponding to some inter-metalli c phases appearing,successively including Al11Nd3,Al3Ni,and some un known phases,in the Al amorphous/crystal matrix. Four peaks appear on the conti nuous heating DSC curves. Their peak temperatures are respectively 470.8,（570. 8,） （585.6,） and 731.6 K at infinitesimal heating rate,and their activation energies of the respective phase transformation are 183.0,294.7,232.5 and 269.1 kJ/mol. The values of Avrami exponent of the four reactions decrease with increasing relative transformation degree. At the earlier stage of phase trans formation,the values of n are larger than 4,and at the later stage the val ues of n become close to some value from 0.5 to 2.0.展开更多
文摘Rapidly solidified ribbons of Al90Nd7Ni3 metallic glasses were prepare d by using melt spinning. Crystallization process of the totally amorphous ribbo ns was investigated by differential scanning calorimetry and X-ray diffraction analysis,under continuous heating regime. The results show that,under continuo us heating regime,the metallic glass devitrifies via two main stages: primary c rystallization,resulting in two-phase mixture of α（Al） plus residual amor phous phase,and secondary crystallization,corresponding to some inter-metalli c phases appearing,successively including Al11Nd3,Al3Ni,and some un known phases,in the Al amorphous/crystal matrix. Four peaks appear on the conti nuous heating DSC curves. Their peak temperatures are respectively 470.8,（570. 8,） （585.6,） and 731.6 K at infinitesimal heating rate,and their activation energies of the respective phase transformation are 183.0,294.7,232.5 and 269.1 kJ/mol. The values of Avrami exponent of the four reactions decrease with increasing relative transformation degree. At the earlier stage of phase trans formation,the values of n are larger than 4,and at the later stage the val ues of n become close to some value from 0.5 to 2.0.
