發(fā)布時(shí)間：2018-01-10 01:25

  本文關(guān)鍵詞：不同長(zhǎng)度短碳纖維增強(qiáng)2024Sc鋁基復(fù)合材料組織及性能研究　出處：《鄭州大學(xué)》2017年碩士論文　論文類(lèi)型：學(xué)位論文

  更多相關(guān)文章： C_f增強(qiáng)鋁基復(fù)合材料 密度 微屈服強(qiáng)度 熱膨脹系數(shù) 力學(xué)性能

【摘要】：本文采用傳統(tǒng)的熔煉鑄造法制備了2024Sc鋁合金,并采用液態(tài)攪拌鑄造法制備質(zhì)量分?jǐn)?shù)為3%長(zhǎng)度分別為2mm、3mm、4mm、5mm短碳纖維增強(qiáng)2024Sc鋁基復(fù)合材料。用化學(xué)鍍銅的方法處理碳纖維,采用掃描電子顯微鏡(SEM)觀(guān)察材料的微觀(guān)組織和拉伸斷口形貌,采用EDS分析材料的微觀(guān)組織中第二相成分,利用阿基米德原理,對(duì)材料的密度、致密化程度進(jìn)行分析,通過(guò)室溫拉伸試驗(yàn)、加載-卸載試驗(yàn)測(cè)量了五種材料雙級(jí)時(shí)效下的常規(guī)力學(xué)性能和微屈服性能,采用熱膨脹儀測(cè)量材料的熱膨脹系數(shù)。結(jié)果表明:(1)鑄態(tài)的2024Sc鋁合金,由于非平衡凝固時(shí)發(fā)生偏析,微觀(guān)組織中有白色連續(xù)網(wǎng)狀的第二相和深灰色α-Al基體組成,在C_f增強(qiáng)復(fù)合材料中觀(guān)察到碳纖維均勻分布在界面上,發(fā)生了輕微的界面反應(yīng)。經(jīng)過(guò)均勻化處理后,連續(xù)白色網(wǎng)狀第二相變成不連續(xù)狀,Zr、Sc部分溶解到基體中,部分以Sc、Zr化合物的形式存在。經(jīng)過(guò)擠壓后,第二相晶粒被拉長(zhǎng)且沿著晶界分布,碳纖維由亂序排列變成沿著擠壓方向分布。(2)研究發(fā)現(xiàn),復(fù)合材料的理論密度和實(shí)際密度均小于2024Sc鋁合金,鑄態(tài)時(shí)的密度均小于擠壓后的密度。隨著碳纖維長(zhǎng)度的增加,復(fù)合材料的鑄態(tài)密度先增加后降低,經(jīng)過(guò)擠壓后復(fù)合材料的密度之間沒(méi)有明顯差異,但是,復(fù)合材料孔隙率明顯降低,孔隙率分別降低了71.3%、59.4%、80.2%和80%。且隨著碳纖維長(zhǎng)度的增加,復(fù)合材料的致密化程度越來(lái)越高,改善了材料的力學(xué)性能。(3)經(jīng)過(guò)495℃/2h固溶,130℃/3h+200℃/(5h、10h、15h)雙級(jí)時(shí)效處理后,研究發(fā)現(xiàn),當(dāng)碳纖維長(zhǎng)度小于5mm時(shí),同種材料的抗拉強(qiáng)度、屈服強(qiáng)度和彈性模量均是先升高后降低,終級(jí)時(shí)效10h時(shí)復(fù)合材料的抗拉強(qiáng)度、屈服強(qiáng)度和彈性模量最大分別為472MPa、411MPa、87GPa;當(dāng)長(zhǎng)度為5mm時(shí),峰時(shí)效時(shí)間提前至5h,抗拉強(qiáng)度和屈服強(qiáng)度分別達(dá)到494MPa、419MPa;當(dāng)鋁合金中添加碳纖維后,材料的抗拉強(qiáng)度、屈服強(qiáng)度和延伸率均下降,但是材料的彈性模量明顯提高,最高為90GPa;復(fù)合材料經(jīng)過(guò)拉伸后,通過(guò)觀(guān)察斷口形貌發(fā)現(xiàn),碳纖維一般被拔出(提前失效)或拔斷。(4)研究發(fā)現(xiàn),微屈服階段時(shí)效硬化率遠(yuǎn)遠(yuǎn)高于屈服階段的時(shí)效硬化率,經(jīng)過(guò)495℃/2h固溶,130℃/3h+200℃/10h雙級(jí)時(shí)效處理后,材料的微屈服達(dá)到最大值。隨著碳纖維長(zhǎng)度的增加,C_f增強(qiáng)復(fù)合材料的微屈服強(qiáng)度先升高后降低,當(dāng)碳纖維長(zhǎng)度為4mm,復(fù)合材料的微屈服強(qiáng)度達(dá)到最大值為304MPa。隨著碳纖維的加入,降低了C_f增強(qiáng)復(fù)合材料的微屈服強(qiáng)度。(5)研究發(fā)現(xiàn),材料相對(duì)伸長(zhǎng)量與溫度變化基本上呈線(xiàn)性關(guān)系。加入碳纖維后,復(fù)合材料的熱膨脹系數(shù)降低,隨著碳纖維長(zhǎng)度的增加,復(fù)合材料的熱膨脹系數(shù)先降低后升高。當(dāng)碳纖維長(zhǎng)度為4mm時(shí),復(fù)合材料的熱膨脹系數(shù)最小,為24.2×10-6/℃。綜合分析可得,當(dāng)碳纖維為4mm時(shí),綜合性能最佳。
[Abstract]:In this paper, 2024Sc aluminum alloy was prepared by traditional melting casting method. The mass fraction of 2024Sc aluminum alloy was prepared by liquid agitation casting method. The length of 2024Sc aluminum alloy was 3% mm ~ 3mm ~ 4mm, respectively. 5mm short carbon fiber reinforced 2024Sc aluminum matrix composites. Carbon fibers were treated by electroless copper plating. The microstructure and tensile fracture morphology of the composites were observed by scanning electron microscopy (SEM). The density and densification degree of the material were analyzed by EDS and Archimedes principle, and the tensile test at room temperature was carried out. The conventional mechanical properties and micro-yield properties of five kinds of materials under two-stage aging were measured by load-unloading test. The thermal expansion coefficient of the material was measured by thermal expansion instrument. The results show that the 2024Sc aluminum alloy in the as-cast state is segregated due to non-equilibrium solidification. The microstructure is composed of white continuous reticular second phase and dark gray 偽 -Al matrix. Carbon fiber is observed to distribute uniformly on the interface in Capf reinforced composites. After homogenization treatment, the second phase of the continuous white reticular form was partially dissolved into the matrix, and the second phase was partially dissolved in the matrix, and the second phase was partially dissolved in the matrix. After extrusion, the grain of the second phase is elongated and distributed along the grain boundary, and the carbon fiber changes from disorderly arrangement to the distribution along the extrusion direction. The theoretical and actual densities of the composites are less than 2024Sc aluminum alloy, and the density of as-cast composites is smaller than that of extruded composites. With the increase of carbon fiber length, the as-cast density of the composites increases first and then decreases. There was no significant difference in the density of the composites after extrusion, but the porosity of the composites decreased obviously, and the porosity decreased by 71.3% and 59.4% respectively. The densification degree of the composites increased with the increase of carbon fiber length, and the mechanical properties of the composites were improved by 495 鈩，

本文編號(hào)：1403328