臺灣博碩士論文加值系統

本研究為探討AA1050商用純鋁經等徑轉角擠形後之微觀結構及機械性質異向性的關係，主要利用通道交角90o及120o的模具，在室溫下進行等徑轉角擠形製程，分別使用三種不同的擠製路徑﹙路徑A、路徑BC、路徑C﹚，以得到超細晶鋁。以穿透式電子顯微鏡定量觀察其微觀結構，並分別改變壓縮試驗的應力軸，以探討其應力受壓縮方向改變的影響。接著再針對以90o通道交角擠製之試片，進行523K退火處理一小時，亦探討其微觀結構及機械性質異向性的關係。此外，並探討經退火處理試片於壓縮測試後，試片表面產生之剪切帶與等徑轉角擠形剪切面的關係。
實驗結果顯示，經不同通道交角及不同擠製路徑進行等徑轉角擠形製程得到的超細晶鋁，具有不同的微結構：長條狀晶粒的比例以路徑A為最高；觀察晶粒尺寸可以發現：(a)使用90o模具擠製的晶粒尺寸小於120o模具擠製；(b)在90o及120o的模具中，皆是路徑C擠製的晶粒尺寸較大，各平面晶粒尺寸皆大於0.58 μm，路徑A與路徑BC類似；(c)在所有的路徑中，Z平面皆有較大的晶粒尺寸，皆大於0.66 μm；(d)最小的晶粒尺寸為0.44 μm，其落在A-8-90-Y及BC-8-90-X平面上。在壓縮測試中可以發現：(a)在90o及120o的模具中，路徑A的壓縮強度較高；(b)在90o及120o的模具中，各路徑的Y方向壓縮強度較高；(c)在路徑BC及路徑C中，使用120o的通道交角所得到的結果，其加工硬化率的表現較佳。
使用90o模具進行ECAE製程的試片作523K退火處理一小時，再進行壓縮測試，可以發現到路徑A仍擁有較高的壓縮強度；經過退火處理後，在應力應變曲線上，可以發現有明顯的降伏下降。經過壓縮測試後，在試片的表面上可以觀察到剪切帶的出現，而此剪切帶皆與各路徑的剪切平面夾有角度，可以知道最後一次擠製的剪切平面不會對剪切帶的形成產生影響。

In this study, ultrafine-grained (UFG) aluminum was processed by equal channel angular extrusion (ECAE) with 90o and 120o dies. The deformation routes are route A, route BC, and route C. The microstructure and anisotropic mechanical properties of UFG aluminum processed by different ECAE die angles and deformation routes were investigated in detail. Additionally, the 90o die deformed specimens were annealed at 523K for 1 hour and tested in compression. Shear bands were observed on the sample surfaces after compression tests. The relationship between shear bands and ECAE shear planes was investigated.
The experimental results indicate that different microstructures were observed in the UFG aluminum. In terms of grain shape, the elongated grain proportion in route A is much higher than the other routes. In terms of grain size: (a) the grain size of the 90o die is smaller than the 120o die; (b) in both dies, the grain size in route A is similar to route BC and it’s much larger in route C (larger than 0.58 μm); (c) in three routes, the grain size is largest on Z plane (larger than 0.66 μm), and (d) the smallest grain size is observed in A-8-90-Y and BC-8-90-X, both are 0.44 μm. In compression tests: (a) in both dies, the compression stress in route A is much higher than the other routes; (b) in both dies, the compression stress along Y-axis is the highest in three routes; (c) in route BC and route C, work hardening rate is higher when the sample was processed with the 120o die.
Compression tests were also performed on the samples annealed at 523K for 1 hour. The compression stress is higher in route A. Yield drop is observed on the stress-strain curves. Shear bands appear on the surface of samples. These shear bands intersect at an angle with compression axis, which indicates that shear plane of the last ECAE process does not influence the evolution of shear bands.

中文摘要 I
英文摘要 II
目錄 III
表目錄 V
圖目錄 VI
第一章 前言 1
第二章 文獻回顧 2
2-1 等徑轉角擠形 2
2-1-1 等徑轉角擠形介紹 2
2-1-2 等徑轉角擠形應變 2
2-1-3 等徑轉角擠形路徑 5
2-1-4 等徑轉角擠形之通道交角 5
2-1-5 等徑轉角擠形之微結構 8
2-2 細晶材料之機械性質 11
2-2-1低延展性 11
2-2-2 超細晶材料之降伏下降(yield drop)現象 17
2-2-3 Shear band 20
2-2-4 等徑轉角擠形材料之異向性 23
2-3 織構 27
第三章 實驗方法 35
3-1 實驗材料 35
3-2 等徑轉角擠形擠製 35
3-3 壓縮測試 35
3-4 退火處理 35
3-5 微硬度測量 36
3-6 微觀組織觀察 36
3-6-1 光學顯微鏡觀察 36
3-6-2 掃瞄式電子顯微鏡觀察 36
3-6-3 穿透式電子顯微鏡試片製備 37
3-7極圖分析 37
第四章 結果 40
4-1 等徑轉角擠形製程後之微結構 40
4-2 退火處理後之微結構 65
4-3細晶AA1050鋁合金之機械性質 79
4-3-1 壓縮測試 79
4-3-2 退火處理後之壓縮測試 85
4-4壓縮測試後之試片表面觀測 89
4-5 微硬度測定 101
4-6 織構分析 103
第五章 結論 111
第六章 參考文獻 113

Alexander David J., Beyerlein Irene J., “Anisotropy in mechanical properties of high-purity copper processed by equal channel angular extrusion”, Materials Science and Engineering A 410–411, 480-484 (2005)

Arruffat-Massion R., Toth L.S., Mathieu J.-P., “Modeling of deformation and texture development of copper in a 120o ECAE die”, Scripta Materialia 54, 1667-1672 (2006)

Beyerlein Irene J., Alexander David J., “Plastic anisotropy in aluminum and cooper pre- strained by equal channel angular extrusion”, J Mater Sci. 42, 1733-1750 (2007)

Carsley J.E., Fisher A., Milligan W.W., Aifantis E.C., “Mechanical behavior of a nanostructured iron alloy”, Metallurgical and Materials Transactions A 29, 2261-2271 (1998)

Cheng S., Spencer J.A., Milligan W.W., “Strength and tension/compression asymmetry in nanostructured and ultrafine-grain metals”, Acta Materialia 51, 4505-4518 (2003)

Ferrasse S., Segal V.M., Kalidindi S.R., Alford F., “Texture evolution during equal channel angular extrusion Part I. Effect of route, number of passes and initial texture”, Materials Science and Engineering A 368, 28-40 (2004a)

Ferrasse S., Segal V.M., Alford F., “Texture evolution during equal channel angular extrusion Part II. An effect of post-deformation annealing”, Materials Science and Engineering A 372, 235-244 (2004b)

Furukawa M., Iwahashi Y., Horita Z., Nemoto M., Langdon T. G., “The shearing characteristics associated with equal-channel angular pressing”, Materials Science and Engineering A 257, 328–332 (1998)

Furukawa M., Horita Z., Langdon T. G., “Factors influencing the shearing patterns in equal-channel angular pressing”, Materials Science and Engineering A 332, 97-109 (2002)

Gholinia A., Prangnell P.B., and Markushev M.V., “The effect of strain path on the development of deformation structures in severely deformed aluminium alloys processed by ECAE”, Acta Materialia 48, 1115-1130 (2000)

Haouaoui M., Karaman I., Maier H.J., “Flow stress anisotropy and Bauschinger effect in ultrafine grained copper”, Acta Materialia 54, 5477–5488 (2006)

Huang W.H., Chang L., Kao P.W., Chang C.P., “Effect of die angle on the deformation texture of cooper processed by equal channel angular extrusion”, Materials Science and Engineering A 307, 113-118 (2001)

Hull D., Bacon D.J., Introduction to dislocations (Butterworth Heinemann Fourth Edition. 2001)

Iwahashi Y., Wang J., Horita Z., Nemoto M., Langdon T. G., “Principle of equal-channel angular pressing for the processing of ultra-fine grained materials”, Scripta Materialia 35, 143-146 (1996)

Iwahashi Y., Horita Z., Nemoto M., Langdon T. G., “An investigation of microstructural evolution during equal-channel angular pressing”, Acta Materialia. 45, 4733-4741 (1997)

Iwahashi Y., Horit Z., Nemoto M., Langdon T. G., “The process of grain refinement in equal-channel angular pressing”, Acta Materialia 46, 3317-3331 (1998)

Nakashima K., Horita Z., Nemoto M. and. Langdon T. G., “Influence of Channel Angle on the Development of Ultrafine Grains in Equal-Channel Angular Pressing”, Acta Materialia, 46,1589(1998).

Randle V., Engler O., Introduction of Texture Analysis: Macrotexture, Microtexture and Orientation Mapping (Overseas Publishers Association 2000)

Reed H., Reza A., Physical Metallurgy Principles (PWS PUBLISHING COMPANY Third Edition 1992)

Segal V.M., “Materials processing by simple shear”, Materials Science and Engineering A 197, 157-164 (1995)

Sun P.L., Cerreta E.K., Gary III G.T., Bingert J.F., “The effect of grain size, strain rate, and temperature on the mechanical behavior of commercial purity aluminum”, Metallurgical and Materials Transactions A 37, 2983-2994 (2006)

Sun P.L., Kao P.W., Chang C.P., “Effect of Deformation Route on Microstructural Development in Aluminum Processed by Equal Channel Angular Extrusion”, Metallurgical and materials transactions A 35, 1359-1368 (2004)

Sun P.L., Yu C.Y., Kao P.W., Chang C.P., “Influence of boundary characters on the tensile behavior of sub-micron-grained aluminum”, Scripta Materialia 52, 265-269 (2005)

Sun P.L., Zhao Y. H., Tseng T. Y., Su J.R., Lavernia E.J., “The influence of cooling rate on the microstructures and mechanical properties in ultrafine-grained aluminum processed by hot rolling”, Materials Science and Engineering A 527, 5287-5294 (2010)

Wang Y.M., Ma E., “Three strategies to achieve uniform tensile deformation in a nanostructured metal”, Acta Materialia 52, 1699-709 (2004)

Wyrzykowski J.W., Grabski M.W., “The Hall- Peach relation on Al and its dependence on the grain boundary structure”, Phil. Mag. 53, 505-520 (1986)

Yu C.Y., Kao P.W., Chang C.P., “Transition of tensile deformation behaviors in ultrafine-grained aluminum”, Acta Materialia 53, 4019-4028 (2005a)

Yu C.Y., Sun P.L., Kao P.W., Chang C.P., “Mechanical properties of submicron-grained aluminum”, Scripta Materialia 52, 359-363 (2005b)

Zhao T.H., Liao X.Z., Cheng S., Ma E., Zhu Y.T., “Simultaneously increasing the ductility and strength of nanostructured alloys”, Acta Materialia 18, 2280-2283 (2006)

Zhu Yuntain Theodore, Lowe Terry C., “Observations and issues on mechanisms of grain refinement during ECAP process”, Materials Science and Engineering A 291, 46–53 (2000)

王允俊，純銅經等徑轉角擠形之低溫退火和機械性質，中山大學碩士論文(2001)

王郁雲，變形溫度對等徑轉角擠製純鋁微組織之影響，中山大學碩士論文(2003)

翁明崑，細晶鋁的疲勞特性研究，中山大學碩士論文(2002)

高文彬，細晶鋁的疲勞組織研究，中山大學碩士論文(2001)

許樹恩，吳泰伯，X光繞射原理與材料結構分析，中國材料科學學會(2004)

曾錫萍，等通道彎角擠製參數對5083鋁合金之影響，中央大學碩士論文(2004)