摘要
We prepare Pd_(40.5)Ni_(40.5)P_(19) glassy samples with purified ingots by copper mold casting at a high cooling rate and by water quenching at a low cooling rate.Both of them exhibit different supercooled liquid regions and multiple glass transition characteristics in their differential scanning calorimetric curves.The plasticity of the glassy sample prepared by copper mold casting is about 5%while that prepared by water quenching is almost zero(0.2%),indicating that cooling rate has influenced the plasticity of glassy alloys.By using high resolution TEM image analysis,it is revealed that there exist characteristic regions with different contrasts in the full glassy samples.The characteristic size is about 20–40nm for the glassy sample prepared by water quenching and 2–4nm for the one prepared by copper mold casting.The large difference in the plasticity of the glassy samples prepared by different cooling rates is believed to be related to the difference in the size of the characteristic nanoscale structures.The results indicate that adjusting cooling rate in preparation of glassy samples could modify the thermal and mechanical properties of the glassy alloys.
基金
by the National Basic Research Program of China under Grant No 2007CB613905
the National Natural Science Foundation of China under Grant Nos 50671050 and 50971073。
