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Title: Ti-6Al-6V-2Sn合金之氣態充氫晶粒細化
Grain Refinement of Ti-6Al-6V-2Sn Alloy by Gas Phase Hydrogenation
Authors: Ying-Jhih Lai
賴盈志
Contributors: NTOU:Institute of Materials Engineering
國立臺灣海洋大學:材料工程研究所
Keywords: 晶粒細化;氣態充氫
refinement
Date: 2008
Issue Date: 2011-06-30T07:23:36Z
Abstract: 以往傳統觀念認為氫在一般材料中被視為一種有害的元素,現在已可經在氫存在環境中由不同熱處理而改善並提升鈦合金機械性質,主要是利用鈦與鈦合金對氫元素之間具有很高的親和力,而氫在鈦合金中主要是以形成固溶氫或形成脆性氫化物的形式存在,再利用氫原子與鈦之間的可逆性,氫原子很容易在高溫高真空的除氫製程中將氫除去,因而達到晶粒細化的成效。 本研究以Ti-6Al-6V-2Sn合金板材為材料,首先利用物理氣態充氫的方式將氫固溶至鈦合金中,在不同充氫條件下其影響參數包含:溫度、氫氣分壓以及充氫時間,探討這些參數對於充氫的影響性。再來針對Froes等人在1990年研究開發的熱化學氣態充氫製程TCT(thermochemical treatment)以及近幾年所稱的熱氫製程THP(thermohydrogen processing),加以探討其顯微組織的變化情形以及比較晶粒細化後機械性質的提升差異性。研究結果顯示,TCT熱化學(直接充氫→除氫)氣態充氫製成主要以細化α相為主,其細化後仍舊維持著層狀組織;THP熱氫製(先充氫→β固溶處理→共析分解→除氫)成則主要以細化β相為主,所得到的細化組織較為針狀被嚴重切割的結構。就機械性質來看以THP熱氫製成細化後的硬度值較TCT熱化學製成細化後所得到的硬度值來的高。
Hydrogen was regard as a harmful element for some general metallic materials in traditional concepts, but it can through different thermochemical procedures to enhance the mechanical properties of titanium alloys. By the presence of hydrogen in titanium to form solid solution or hydride, titanium and titanium alloys have large affinity for hydrogen and can be easily to removed by vacuum annealing. The dissolving and removing processes of hydrogen in titanium alloy is reversible, so that results grain refinement of its alloys. In this study, that hydrogenation in different effective parameters has been discussed, including: temperature, hydrogen pressure and hydrogenation time, by gas phase hydrogenation. TCT(thermochemical treatment) was firstly develop by Froes in 1990s and then modified and renamed it as THP(thermohydrogen processing). It can be evaluated through the microstructure variation and enhance the mechanical processability of titanium alloys by the degree of grain refinement.
URI: http://ethesys.lib.ntou.edu.tw/cdrfb3/record/#G0M95550014
http://ntour.ntou.edu.tw/ir/handle/987654321/13592
Appears in Collections:[材料工程研究所] 博碩士論文

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