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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/80650


    Title: 高含量Ti、B對A201-T7鋁合金熱裂性、微結構與機械性質的影響;Effect of high Ti and B content on the hot tearing, microstructure and mechanical properties of A201-T7 aluminum alloys
    Authors: 陳勉中;Chen, Mian-Chung
    Contributors: 材料科學與工程研究所
    Keywords: 鋁銅合金;鋁鈦硼中間相;低熱膨脹係數;抗熱裂性;Al-Cu alloy;intermetallic compounds;low thermal expansion coefficient;hot tearing resistance
    Date: 2019-07-11
    Issue Date: 2019-09-03 14:49:59 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 摘要

    本研究藉由熱裂測試、光學顯微鏡(OM)、電子微探儀(EPMA)、導電度(%IACS)、機械性質(硬度、拉伸)試驗等,探討高含量Ti(3.0wt%)、B(1.4wt%)對高強度鑄造A201 (Al-4.5Cu-0.7Ag-0.3Mg) 合金之鑄造熱裂性、微結構、與機械性質之影響。
    結果顯示,由於高含量Ti(3.0wt%)、B(1.4wt%)的添加,細化了鑄態合金晶粒,平均尺寸由105μm下降至45μm,且於鋁基地中生成TiB2、Al3Ti等中間相。當進行過時效處理(T7)後,合金強度與硬度約為418MPa與83HRB,相較於未改質合金,分別提升了7.1%與15%。顯示中間相雖具有散佈強化合金之效果,但對於添加高Ti、B的熱處理型A201合金而言,其提升強度與硬度仍屬有限。
    藉由熱裂模具分析鑄造性後,發現合金抗熱裂性顯著提升,試棒完好數量由零根增加至三根,裂縫形貌由完全斷裂轉為細小裂縫。另外,相較於單獨添加,若同時添加Ti、B於合金中,由於極低膨脹係數的TiB2中間相生成之緣故,使合金具有最佳的鑄造性。



    關鍵字: 鋁銅合金、鋁鈦硼中間相、低熱膨脹係數、抗熱裂性

    ;Abstract

    This research presents the effect of high Ti (3.0wt%) and B (1.4wt%) content on the hot tearing, microstructure and mechanical properties of high strength A201(Al-Cu-Ag-Mg) aluminum alloys, the analyzed methods including hot tearing test, optical microscope (OM), electron probe micro analyzer (EPMA), electrical conductivity meter (% IACS), tensile test...ellipses.
    The results showed the average grain size of as-cast state alloys decreased from 105μm to 45μm due to high Ti (3.0wt%) and B (1.4wt%) added. Besides, the intermetallic compounds such as TiB2, Al3Ti formed in the Al-Matrix. Compared to unmodified alloys, the tensile strength and hardness of high Ti and B content alloys increased about 7.1% and 15% after T7 heat treatment, up to 418MPa and 83HRB. Showed the improvements of mechanical properties on high Ti and B content heat-treatable A201 alloys was slight, although the intermetallic compounds had dispersion strengthening effect.
    Castability was analyzed by hot tearing molds and the results showed the resistance of hot tearing improved significantly. The amount of unbroken test bar of modified alloys is three while the un-modified alloys is zero. The hot cracks morphology also indicated the resistance of hot tear improved with the addition of high Ti and B. Besides, compared to add Ti or B lonely, the alloys has the best castability while Ti and B were added together. That’s because the formation of the intermetallic compounds TiB2 which has low thermal expansion coefficient can improve the hot tearing resistance.


    Keywords: Al-Cu alloy, intermetallic compounds, low thermal expansion coefficient, hot tearing resistance
    Appears in Collections:[材料科學與工程研究所 ] 博碩士論文

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