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Pd能用来作为添加元素改善Ti-Zr-Ni准晶合金的吸氢性能,但是Pd添加的作用机制仍然不清楚。本工作通过采用XRD、TEM、DSC分析技术研究了Pd在Ti45Zr38Ni17和Ti40Zr40Ni20两个合金中对Ti、Zr的替代行为。结果显示:在前1个合金中,替代4%~6%(原子分数,下同)Ti或4%Zr能够确保纯二十面体准晶形成;在后一个合金中,替代3%~4%Ti或3%以下Zr才能形成纯二十面体准晶。这说明Ti具有更高的替代极限。Ti39Zr38Ni17Pd6与Ti36Zr40Ni20Pd4两个衍生准晶合金在400℃温度下退火会转变为晶体相,而它们的初始准晶合金Ti45Zr38Ni17和Ti40Zr40Ni20在400℃仍然结构稳定,这反映出添加Pd后准晶合金的热力学稳定性变低。这种替代趋势和准晶稳定性的降低很可能归功于Pd具有适宜的原子尺寸。
Pd can be used as an additive element to improve the hydrogen absorption performance of Ti-Zr-Ni quasicrystalline alloys, but the mechanism of action of Pd addition remains unclear. In this work, the Ti, Zr substitution behavior of Pd in two alloys Ti45Zr38Ni17 and Ti40Zr40Ni20 was investigated by XRD, TEM and DSC techniques. The results show that in the first alloy, instead of 4% ~ 6% (atomic fraction, the same below) Ti or 4% Zr can ensure pure icosahedral quasicrystal formation; in the latter alloy, instead of 3% ~ 4% Ti or less than 3% Zr to form pure icosahedral quasicrystals. This shows that Ti has a higher substitution limit. The two derived quasicrystalline alloys, Ti39Zr38Ni17Pd6 and Ti36Zr40Ni20Pd4, annealed at 400 ℃ transformed into crystalline phases, while their initial quasicrystalline alloys Ti45Zr38Ni17 and Ti40Zr40Ni20 were still structurally stable at 400 ℃, which reflects the thermodynamic stability of the quasicrystalline alloy after addition of Pd Sex becomes low. This reduction in the tendency toward substitution and quasi-crystal stability is most likely attributed to the proper atomic size of Pd.