Rapidly solidified ribbons of Al_(90)
Nd_7Ni_3 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 Al_(11)Nd_3,Al_3Ni,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.
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