添加微量Sc的Al-Y-Ni非晶合金熱穩定性與機械性質之研究

本研究以單輥熔射旋淬法製備(Al87Y8Ni5)(下標 100-X)Sc(下標 X)（X=0, 0.5, 1, 1.5及2 at.%）合金薄帶，期藉由添加Sc元素來改善Al-Y-Ni合金的非晶形成能力，增強其機械性質。當Sc元素的添加量由0at%增至2.0 at.%時，經由XRD及SEM的檢測及觀察，確認合金薄帶皆具有非晶質的結構，薄帶微硬度值隨著Sc添加量的增加，其值由350H(下標 v)增至430 H(下標 v)；在非晶熱穩定性上，Al87Y8Ni5合金薄帶隨著Sc添加量的增加，初始結晶溫度有往高溫向移動之趨勢；利用Kissinger equation計算非晶態的結晶活化能，結果顯示隨著Sc添加量由0at.%增加至2 at.%時，結晶活化能從159 kJ/mole提升至241 kJ/mole。由實驗中得知，隨著Sc添加量的增加，使得合金的液態組織結構更無序且緊密堆積，造成原子的擴散遷移需更多的能量，抑制凝固過程中結晶相的形核及成長，產生細微晶粒及非晶質之複合組織結構，引起細晶析出強化的效果，故機械性質隨之增強。

關鍵字

熱穩定性；機械性質；結晶活化能

並列摘要

Effects of' glass Forming ability by scandium addition to Al-Y-Ni amorphous alloy were investigated in this study. The alloy ribbons of (Al87Y8Ni5)(subscript 100-x) Sc(subscript x) (X=0, 0.5, 1.0, 1.5 and 2.0 at.%) were prepared by single roller melt-spinning method, and alloy rods were prepared by inductance casting. With up to 2 at.% addition of scandium, the ribbon was confirmed amorphous by XRD and SEM observations. The hardness increased with the addition of scandium and ranged between 350 H(subscript v) and 440 H(subscript v). Thermal stability of amorphous nickel-yttrium aluminum ribbons appeared to rise with the concentration of scandium. The crystallization temperature of ribbons also increased with scandium addition. 2 at.% of scandium was also found to increase the crystallization activation energy from 159 kJ/mole to 241 kJ/mole. For rods, the highest cooling rate is obtained at the surface near the copper mold where no significant crystallization was observed and microhardness of 340H(subscript v) was achieved. Crystallization increased with the distance away from the copper mold where the microhardness reduces to about 220H(subscript v). The percentage of nano-crystallites increased with the addition of scandium and gave rise to grain refinement and increased mechanical properties.

並列關鍵字

Thermal Stability ； Mechanical Properties ； Crystallization ActivationEnergy

國際替代計量

添加微量Sc的Al-Y-Ni非晶合金熱穩定性與機械性質之研究

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