『奈米高熵合金』即至少以五個主要元素配置合金，每個主要元素含量至少超過5 at%，但最多不超過35 at %。有別於傳統合金系統，高熵合金乃是以創新的合金設計概念來配置合金元素，且具有優異的機械強度，有潛力成為高溫材料之主要選擇，以助於高溫高效率發電系統上之研發。
□本論文主要目的是研究新發展之奈米高熵合金應用於先進核反應器之可行性。高熵合金系統種類繁多，本研究所使用的系統為Ti0.5CrCo1.5FeNi1.5五元高熵合金。為了解高溫高能量粒子照射下，材料之輻射損傷效應，本研究規劃了一系列的實驗，以加速器離子束作為輻射損傷模擬的粒子射源，使用鋁正三價離子而在1.26um處達到10dpa之損傷，配合TEM觀察微結構之變化進而評估其對材料性質之影響。由實驗結果發現：奈米高熵合金其微結構並不複雜，多主元素原子仍可排成FCC晶格且具有可分析及鑑定的特性，為典型之奈米結構。由於多個主成分之影響，造成晶格扭曲，使XDR繞射強度下降﹔且具有罕見的高溫析出硬化現象，在800℃、10 h的時效處理下硬度為未時效前的1.33倍，此硬化的現象歸因於γ’相的析出。另外，由TEM觀察到η相在高溫的析出與成長，其中η與母相γ有特定的取向關係為[112] γ // [0001] η 及 (1 1) γ // (10 0) η。在低於700℃進行照射實驗，在照射區域內發現缺陷團的出現，缺陷團的尺寸及數密度會受到照射溫度的影響。溫度約高則缺陷尺寸越大，在10dpa的劑量下400℃至700℃內缺陷尺寸對溫度的變化為5.811×10-3nm/℃﹔缺陷尺寸也隨著劑量增加而變大，500℃下缺陷大小對劑量變化之斜率為0.167nm/dpa，而700的斜率為0.154nm/dpa。缺陷團數密度也會受到照射溫度的影響500℃照射時缺陷總數密度對劑量的斜率為2.666×1021/dpa﹔而700℃照射時斜率為2.333×1020/dpa 。700、800、900℃,10dpa之劑量照射下，只有在700℃照射條件下於佈植區內發現糾結之差排與點缺陷聚集體（直徑小於10nm），這可能是因為800,900℃溫度太高使得缺陷退火回復消失。

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