(中國石油大學(xué)(華東) 機電工程學(xué)院，青島 266580)
摘 要: 采用真空電弧熔煉法熔煉出Al0.5CoCrFeNiTi0.5高熵合金，并在600、800和1000 ℃下進(jìn)行真空退火熱處理。利用X射線衍射儀(XRD)、光學(xué)顯微鏡(OM)、電子探針(EPMA)、硬度計、萬能試驗機以及電化學(xué)工作站對合金鑄態(tài)和不同溫度退火態(tài)的微觀組織、硬度、壓縮力學(xué)性能以及在3.5% NaCl溶液中的耐蝕性進(jìn)行研究。組織分析表明：鑄態(tài)和退火態(tài)的Al0.5CoCrFeNiTi0.5合金均由富(Cr，F(xiàn)e)的FCC、富(Al，Ni，Ti)的BCC和σ三相組成，但退火處理使合金的組織形貌和各相的相對含量發(fā)生了改變，鑄態(tài)下的粗大白色FCC柱狀晶轉(zhuǎn)變?yōu)榧?xì)小的FCC+BCC+σ的混合組織；隨著退火溫度的升高，BCC和σ相含量增加。800 ℃退火態(tài)合金成分均勻性最好，1000 ℃退火態(tài)合金由于退火溫度過高，組織粗大，元素偏析重新加劇。硬度試驗和壓縮試驗結(jié)果表明：合金在鑄態(tài)和3種溫度退火態(tài)下的硬度都較高，表現(xiàn)出良好的抗回火軟化能力；800 ℃退火態(tài)合金中由于BCC和σ相的增加，其硬度和屈服強度最高，但塑性最差。1000 ℃退火態(tài)合金由于大量σ相的析出以及組織粗大，其屈服強度、斷裂強度和壓縮形變率都急劇降低。600 ℃退火態(tài)合金具有理想的FCC、BCC和σ相的組成含量，其綜合力學(xué)性能最好。電化學(xué)腐蝕試驗表明：鑄態(tài)和3種溫度退火態(tài)的合金在3.5% NaCl溶液中都表現(xiàn)出良好的耐蝕性，800 ℃退火態(tài)合金由于其成分均勻性最好，耐蝕性最好。
關(guān)鍵字: 高熵合金；退火；組織結(jié)構(gòu)；力學(xué)性能；耐蝕性
（College of Mechanical and Electronic Engineering, China University of Petroleum (Huadong), Qingdao 266580, China）
Abstract:Al0.5CoCrFeNiTi0.5 high entropy alloys were prepared by vacuum arc melting and were treated by vacuum annealing at 600, 800 and 1000 ℃ for 10 h. The microstructure, mechanical properties and corrosion resistance in the 3.5% NaCl solution of the as-cast and annealed alloys were studied by XRD, OM, EPMA, hardness tester, universal testing machine, and electrochemical workstation. The microstructure analysis shows that the as-cast and three kinds of annealed alloys are all composed of FCC rich (Cr, Fe), BCC rich (Al, Ni, Ti) and σ, but their microstructure morphologies and the relative contents of each phase are different. As the annealing process, the thick white FCC columnar crystals in the as-cast alloy shift to the mixed structures of FCC, BCC and σ, and with the increase of annealing temperature, the contents of the BCC and σ phase increase. The 800 ℃-annealed alloy has the best composition uniformity, and the 1000 ℃-annealed alloy has the increasing element segregation and the coarse microstructure due to the high annealing temperature. The hardness and compression tests show that all of the as-cast and three kinds of annealed alloys have high hardness, showing good resistance to tempering softening, the 800 ℃-annealed alloy has the highest hardness and yield strength but its plasticity is the worst due to the increase of the BCC and σ phase content, the yield strength, fracture strength and compressive deformation rate of the 1000 ℃-annealed alloy sharply decrease due to its coarse structure and a large number of σ precipitation, the 600 ℃-annealed alloy has the best comprehensive mechanical properties due to the ideal contents of FCC, BCC and σ. The electrochemical corrosion tests show that the as-cast and three kinds of annealed alloys all have good corrosion resistance in 3.5% NaCl solution and the corrosion resistance of the 800 ℃-annealed alloy is the best because of its best composition uniformity.
Key words: high-entropy alloy; annealing; microstructure; mechanical property; corrosion resistance
