【摘要】：高熵合金的設(shè)計(jì)理念相對(duì)于傳統(tǒng)的多元合金來說是一種創(chuàng)新性的突破,通常主元元素種類不少于五種,每種元素的含量不少于5%且不超過35%,因此擁有與傳統(tǒng)合金不同的組織和性能。高熵合金各元素之間起協(xié)同作用,故每種元素的種類和含量的變化都會(huì)引起高熵合金組織、結(jié)構(gòu)和性能的變化。因此通過調(diào)整合金元素的種類和含量得到高性能高熵合金,具有特別重要的理論和實(shí)踐意義。本文采用真空電弧熔煉爐和銅模澆鑄法制備了 AlxFeCrCoNi(Cy)、CoCrFeNiMnCx和CoFeNiMnCx系高熵合金,同時(shí)采用真空管式熱處理爐進(jìn)行熱處理。然后采用光學(xué)顯微鏡、XRD衍射儀、掃描電鏡和透射電鏡分析了 A1和C元素對(duì)FCC高熵合金的相結(jié)構(gòu)和微觀組織的影響。其次采用顯微硬度儀和電子萬能試驗(yàn)機(jī)測試了合金的維氏硬度和拉伸性能。得出了如下結(jié)論:在AlxFeCrCoNi(Cy)系高熵合金中,隨著A1元素含量的增加,當(dāng)x≤0.3時(shí)合金的晶體結(jié)構(gòu)為面心立方結(jié)構(gòu);當(dāng)x=0.4開始出現(xiàn)BCC相,BCC相隨A1元素含量的增加而增加。當(dāng)x≤0.2時(shí)金相組織為胞狀樹枝晶;當(dāng)x=0.3時(shí)金相組織為轉(zhuǎn)變?yōu)橹鶢顦渲?當(dāng)x≥0.4時(shí)金相組織為等軸樹枝晶。在1100℃保溫24h熱處理后,在AlxFeCrCoNi(x=0.4,0.5)系高熵合金的晶內(nèi)出現(xiàn)大量針狀BCC相。少量A1元素的添加會(huì)同時(shí)提高合金強(qiáng)度和塑性,當(dāng)x≥0.3時(shí)合金的強(qiáng)度升高但塑性降低。此外,隨著C元素的添加,合金產(chǎn)生新相M7C3,提高強(qiáng)度的同時(shí)降低塑性。C元素可以提高A1原子在AlxFeCrCoNi(Cy)系高熵合金中的固溶度。綜合力學(xué)性能最佳的合金為Al0.4CoCrFeNiC0.05,其屈服強(qiáng)度、抗拉強(qiáng)度和延伸率分別為330MPa、621MPa和56%。在CoCrFeNiMnCx系高熵合金中,少量C元素的添加(x≤0.05),合金的晶體結(jié)構(gòu)仍然為FCC,合金的強(qiáng)度和塑性得到改善;當(dāng)x≥0.1時(shí),產(chǎn)生新相M7C3,合金的強(qiáng)度升高,塑性降低。且隨著C元素含量的增加,碳化物由細(xì)桿狀變?yōu)槠瑺?分布于晶界或者晶界旁邊。CoCrFeNiMnC0.05合金在高應(yīng)變下會(huì)出現(xiàn)大量納米級(jí)變形孿晶。微量C元素可以使由位錯(cuò)滑移主導(dǎo)的塑性變形過渡為由位錯(cuò)滑移和孿晶組成的混合變形模式。熱處理后,合金會(huì)出現(xiàn)新相M23C6,合金強(qiáng)度和塑性降低。在CoFeNiMnCx系高熵合金中,隨著C元素的添加,點(diǎn)陣常數(shù)升高,但合金的晶體結(jié)構(gòu)依然為FCC。強(qiáng)度隨C含量的增加而升高,塑性則小幅度的降低。綜合力學(xué)性能最佳的合金為CoFeNiMnCo.2,其屈服強(qiáng)度、抗拉強(qiáng)度和延伸率分別為521MPa、778MPa和38%。在1200℃保溫48h熱處理后產(chǎn)生調(diào)幅分解,合金的強(qiáng)度和塑性進(jìn)一步提高。
[Abstract]:The design concept of high entropy alloy is a kind of innovative breakthrough compared with traditional multicomponent alloy, usually there are not less than five kinds of principal element. Each element contains not less than 5% and does not exceed 35%, so it has different microstructure and properties from traditional alloys. There is a synergistic effect among the elements of the high entropy alloy, so the change of the type and content of each element will cause the changes of the structure, structure and properties of the high entropy alloy. Therefore, it is of great theoretical and practical significance to obtain high performance and high entropy alloy by adjusting the kinds and contents of alloying elements. In this paper, AlxFeCrCoNi (Cy) CoCrFeNiMnCx and CoFeNiMnCx system high entropy alloys were prepared by vacuum arc melting furnace and copper mold casting, and the vacuum tube heat treatment furnace was used for heat treatment. The effects of Al and C on the phase structure and microstructure of FCC high entropy alloy were analyzed by means of optical microscope, scanning electron microscope and transmission electron microscope. Secondly, the Vickers hardness and tensile properties of the alloy were tested by microhardness tester and electronic universal tester. The following conclusions are drawn: with the increase of A1 element content, the crystal structure of AlxFeCrCoNi (Cy) system is face-centered cubic structure when x 鈮，

本文編號(hào)：2223562