氢化热处理对Ti6Al4V合金奈米晶粒细化研究NanograinRefinement.PDF

氫化熱處理對Ti6Al4V 合金奈米晶粒細化研究 Nanograin Refinement in Ti6Al4V by Thermal Hydrogenation Processing * 沈家傑(Chia-Chieh Shen) , 王仲敏(Chung-Min Wang), 陳欣鴻(Shin-Hung Chen) 元智大學機械工程學系 Department of Mechanical Engineering, Yuan Ze University *Email: ccshen@saturn.yzu.edu.tw 本論文研究氫化熱處理對於雙相(α+β)等軸晶Ti6Al4V 之奈米晶粒細化研究。氫化熱處理 包含在恆溫600 OC 條件，以Sievert 系統精準製備吸氫量從0.1 至0.9 H/M 範圍之六個氫化鈦 試片，再以真空幫浦脫氫處理使氫化鈦恢復至原始的雙相組成。實驗結果顯示，吸氫量低於 0.7 H/M 的試片，α 晶粒內皆發現到50-100 nm 的片狀細化晶粒，此奈米晶粒密度隨著吸氫量 的增加而變高，同時促進Ti6Al4V 的硬化，在吸氫量0.6 H/M 的條件，試片硬度值達到最高 值390 Hv ，另一方面，超過0.7 H/M 的吸氫條件，試片內部發生寬度約數微米的裂紋，不利 於試片的硬化。由Ti6Al4V-H 相圖的分析，上述的奈米片狀細化晶粒應來自於Ti6Al4V-H 氫 化鈦的析出及移除所伴隨的相變化所貢獻，而裂紋應是-氫化鈦析出時所帶來巨大應變能而 引起的氫脆現象。 關鍵詞： 氫化熱處理、晶粒細化、奈米結構、機械性質 The influence of titanium hydrides on the grain refinement and mechanical properties of Ti6Al4V (+) alloy was investigated. Formation and removal of  and  (fcc) hydrides were used H to refine the equiaxed microstructure of Ti6Al4V. Formation of the hydrides having  + ,  and H H H  + were made precisely by charging hydrogen loadings ranged from 0-0.1, 0.3-0.6 and 0.7-0.9 H H/M, respectively, in a Sievert’s apparatus at T = 600 oC. X-ray diffraction (XRD) analyses showed that all dehydrogenated specimens have been restored to original  and  without any residual titanium hydride. Scanning electron micrographs show that strip-like nanostructures with the thickness from 50 to 100 nm were produced within the original α grain. The volumetric density of the observed nanostructure increases with the hydrogen loading, supported with the enlargement of the peak broadening of α (102) in XRD. Similar, the measu