氧化鋁短纖強化鋁基複合材料(Al-Zn-Mg/Al-2O3(f))高溫機械性質之研究

Abstract

本研究係以擠壓鑄造法(squeeze casting)製作鋁基複合材料，基材為鋁 鋅鎂合金，強化材採用氧化鋁短纖。實驗目的是探討氧化鋁短纖強化相及 析出強化相，對鋁基複合材料高溫機械性質之影響。在鑄造的過程中添加 適量的鎂元素，以控制基地中的鎂含量(2.22wt%~3.08wt%)。鋁鋅鎂合金 與複合材料經480℃48小時之固溶化處理，再於120℃油浴分別進行72與24 小時之人工時效處理，以期達到最佳之強度。實驗結果顯示，複合材料中 的氧化鋁短纖強化使得在高溫(200℃)的抗拉強度優於鋁鋅鎂合金百分之 十。氧化鋁短纖的存在，使複合材料的動態應變時效現象較鋁鋅鎂合金劇 烈。磨耗實驗顯示，鋁鋅鎂合金的輕度磨耗轉變為嚴重磨耗之轉變溫度 為250℃，而複合材料則高於250℃，即複合材料有較優之高溫耐磨耗性。 In this study ,aluminium matrix composites were fabricated by squeeze casting .In the composites,the matrix was Al-Zn-Mg alloy and the reinforcement was alumina short fiber. The content of magnesium was varied in the range from 2.22wt% to 3.08wt%.The subject was to investigate the effect of alumina short fiber and precipitate phase on the composite at elevated temperature .To obtain an optimum mechanical behavior,the alloys and the composites were treated by solute treatment at 480℃for 48 hours and artific The results showed the tensile strength of the composites was more than that of the alloy over 10% at 200℃.The phenomenom of the dynamic strain aging was also more obvious on the composite owing to th alumiua fiber. It was found that a mild to severe wear transition when the surrounding temperature was at 250℃for alloys and over 250℃for composites from the wear experiment.It meant that the composites exhibited a better wear resistance than alloys at elevated temperature.