【摘要】：本論文的研究對(duì)象為鑄態(tài)AlFeCoCrNi高熵合金及不同預(yù)壓量的合金,表征了不同直徑及不同預(yù)壓量高熵合金的微觀結(jié)構(gòu),研究了不同直徑AlFeCoCrNi高熵合金在變載荷下在空氣中的磨損行為,同時(shí)研究了AlFeCoCrNi高熵合金及不同預(yù)壓量的合金在模擬海水及1mol/L鹽酸中的腐蝕行為,探索了高熵合金在兩種溶液中的腐蝕機(jī)理。借助透射電子顯微鏡(TEM)觀察了AlFeCoCrNi高熵合金及不同預(yù)壓量的合金的結(jié)構(gòu),高熵合金的組織內(nèi)出現(xiàn)了大量的納米析出相,隨冷卻速度的增大,析出相尺寸逐漸變得細(xì)小,由小塊狀變?yōu)獒槧?隨預(yù)變形量的增加,高熵合金未發(fā)生相變,但組織由圓狀逐漸拉長為長條狀。對(duì)不同直徑AlFeCoCrNi高熵合金的顯微維氏硬度進(jìn)行了測試,高熵合金的硬度隨冷卻速度的增加而升高,直徑為2mm的高熵合金達(dá)到最大值。結(jié)合磨損面形貌圖、質(zhì)損量和摩擦系數(shù)綜合評(píng)價(jià)了AlFeCoCrNi高熵合金在空氣中的耐磨損性能。AlFeCoCrNi高熵合金在空氣中的表面粗糙程度、質(zhì)損量及摩擦系數(shù)隨合金的冷卻速度的增加而減小,直徑為2mm的高熵合金達(dá)到相對(duì)最小值,以上結(jié)果表明,直徑為2mm的高熵合金在空氣中的耐磨損性能最好;高熵合金在空氣中磨損時(shí),隨摩擦過程中載荷的增大,其磨損機(jī)制由磨粒磨損逐漸變?yōu)檠趸p和粘著磨損。結(jié)合阻抗譜和極化曲線綜合評(píng)價(jià)了鑄態(tài)及不同預(yù)壓量AlFeCoCrNi高熵合金在模擬海水和1mol/L鹽酸中的腐蝕行為。極化試驗(yàn)表明,在兩種腐蝕溶液中,AlFeCoCrNi高熵合金的抗腐蝕性能隨預(yù)壓量的增大先增加后減小,預(yù)壓量為13%的高熵合金的自腐蝕電流密度最小;阻抗試驗(yàn)表明,13%預(yù)壓量高熵合金在二種溶液中的電荷轉(zhuǎn)移電阻、阻抗值及容抗弧直徑最大,預(yù)壓量為13%的高熵合金在二種溶液中的耐腐蝕性能最優(yōu),并且在模擬海水和1mol/L鹽酸中較304不銹鋼優(yōu)異。采用掃描電子顯微鏡(SEM)觀測到預(yù)壓量為13%的高熵合金在兩種溶液中具有最少最淺的點(diǎn)蝕坑,能譜分析結(jié)果顯示,鑄態(tài)及不同預(yù)壓量AlFeCoCrNi高熵合金的腐蝕區(qū)域均存在Al、Fe、Cr、Ni元素的溶解以及Co元素的富集。采用X射線光電子能譜測試了高熵合金在模擬海水中腐蝕后的表面電子結(jié)構(gòu),預(yù)壓量為13%的高熵合金表面產(chǎn)生富含Al~(3+)、Ni~(2+)、Cr~(3+)的致密氧化膜。
[Abstract]:In this paper, as cast AlFeCoCrNi high entropy alloy and different preloading alloy are studied. The microstructure of AlFeCoCrNi high entropy alloy with different diameters and different preloading amounts is characterized, and the wear behavior of AlFeCoCrNi high entropy alloy with different diameters in air under variable load is studied. At the same time, the corrosion behavior of AlFeCoCrNi high entropy alloy and different preloading alloy in simulated seawater and 1mol/L hydrochloric acid was studied, and the corrosion mechanism of high entropy alloy in two solutions was explored. The structure of AlFeCoCrNi high entropy alloy and the alloy with different preloading amounts were observed by means of transmission electron microscope (TEM). A large number of nanocrystalline precipitates appeared in the microstructure of the high entropy alloy, and the size of the precipitated phase became smaller with the increase of cooling rate. From a small block to a needle; With the increase of predeformation amount, the high entropy alloy does not undergo phase transformation, but the microstructure is gradually elongated from a circular shape to a long strip. The microhardness of AlFeCoCrNi high entropy alloy with different diameters was tested. The hardness of high entropy alloy increased with the increase of cooling rate, and the maximum value of high entropy alloy with diameter of 2mm was obtained. The wear resistance of AlFeCoCrNi high entropy alloy in air was evaluated by means of wear surface topography, mass loss and friction coefficient. The surface roughness of AlFeCoCrNi high entropy alloy in air was evaluated. The mass loss and friction coefficient decrease with the increase of cooling rate of the alloy, and the high entropy alloy with diameter of 2mm reaches the relative minimum. The above results show that the high entropy alloy with diameter 2mm has the best wear resistance in air. With the increase of friction load, the wear mechanism of high entropy alloy changes from abrasive wear to oxidation wear and adhesion wear. The corrosion behavior of as-cast and pre-loaded AlFeCoCrNi high entropy alloys in simulated seawater and 1mol/L hydrochloric acid was evaluated by means of impedance spectroscopy and polarization curves. Polarization test shows that the corrosion resistance of AlFeCoCrNi high entropy alloy increases first and then decreases with the increase of preloading, and the corrosion current density of high entropy alloy with 13% preloading is the smallest. The impedance test shows that the charge transfer resistance, impedance and capacitance arc diameter of 13% prepress high entropy alloy are the largest in both solutions, and the corrosion resistance of high entropy alloy with 13% prepress is the best in both solutions. It is superior to 304 stainless steel in simulated seawater and 1mol/L hydrochloric acid. Using scanning electron microscope (SEM), it was observed that high entropy alloy with preloading amount of 13% had the smallest and shallowest pitting pit in both solutions. The results of energy spectrum analysis showed that there was Al,Fe, in the corrosion zone of AlFeCoCrNi high entropy alloy with as cast and different preloading amounts. Dissolution of Cr,Ni elements and enrichment of Co elements. The surface electronic structure of high entropy alloy after corrosion in simulated seawater was measured by X-ray photoelectron spectroscopy (XPS). A dense oxide film rich in Al~ (3), Ni~ (2) and Cr~ (3) was produced on the surface of high entropy alloy with preloading of 13%.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG172;TG139

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本文編號(hào)：2303672