(1. 陜西科技大學(xué) 陜西省無機材料綠色制備與功能化重點實驗室，西安 710021；
2. 陜西科技大學(xué) 輕工科學(xué)與工程學(xué)院，西安 710021；
3. 西北工業(yè)大學(xué) 凝固技術(shù)國家重點實驗室，西安710072)
摘 要: 采用真空非自耗電弧熔煉法制備了兩種系列的Laves相Cr-Nb-Si(Al)合金，利用掃描電鏡(SEM)、能譜儀(EDS)、Vickers硬度計及萬能力學(xué)試驗機研究了合金的顯微組織、力學(xué)性能及強韌化機理。結(jié)果表明：隨著Al含量不斷增加，合金Cr-45Nb-xAl(x=0, 7.5, 17.5)的顯微組織由初生相Cr2Nb+共晶Cr2Nb/Nb固溶體(Nbss)演變?yōu)槿簿r2Nb/Nbss；而隨著Si含量不斷增加，合金Cr-57.5Nb-xSi(x=0, 5, 10)的顯微組織由初生相Nbss+共晶Cr2Nb/Nbss演變?yōu)楹Ｔ?樹枝晶共晶，樹枝晶內(nèi)部為兩相共晶Cr2Nb/Nbss，樹枝晶邊緣為三相共晶Cr2Nb/Nb5Si3/Nbss。合金Cr-45Nb-xAl(x=0, 7.5, 17.5)的壓縮強度與斷裂韌性隨Al含量增加不斷減小，而合金Cr-57.5Nb-xSi(x=0, 5, 10)的壓縮強度與斷裂韌性隨Si含量增加呈現(xiàn)先增大后減小的趨勢，壓縮強度與斷裂韌性在Cr-57.5Nb-5Si合金均達到最大值，其值分別為2.5 GPa和15 MPa？m1/2。合金Cr-57.5Nb-5Si優(yōu)異的強韌性源于析出強化、界面強化、固溶強化、第二相增韌及合金化增韌的協(xié)同作用。
關(guān)鍵字: Laves相合金；顯微組織；力學(xué)性能；強韌化機理
（1. Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic Materials, Shaanxi University of Science and Technology, Xi’an 710021, China;
2. College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science and Technology, Xi’an 710021, China;
3. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China）
Abstract:Two series of Laves phase alloys Cr-Nb-Si(Al) were prepared by vacuum non-consumable arc melting, and various techniques including SEM, EDS, a Vickers hardness tester, and a universal mechanical testing machine were conducted to study the microstructures, the mechanical properties, and the underling strengthening and toughening mechanisms of these alloys. The results showed that, the microstructures of alloys Cr-45Nb-xAl(x=0, 7.5, 17.5) evolved from primary Cr2Nb plus eutectic Cr2Nb/Nbss to full eutectic Cr2Nb/Nbss with increasing Al content, whereas the microstructures of alloys Cr-57.5Nb-xSi(x=0, 5, 10) transited from primary Nbss plus eutectic Cr2Nb/Nbss to dendritic eutectic. The eutectic within the dendrite was Cr2Nb/Nbss, while transforming to Cr2Nb/Nb5Si3/Nbss at the margin of dendrite. The compression strength and fracture toughness of alloys Cr-45Nb-xAl(x=0, 7.5, 17.5) decreased with increasing Al content, whereas increased firstly and decreased subsequently with increasing Si in the alloys Cr-57.5Nb-xSi(x=0, 5, 10). The compression strength and fracture toughness reached its maximum in the alloy Cr-57.5Nb-5Si and estimated as 2.5 GPa and 15 MPa？m1/2, respectively. The excellent combination of strength and toughness of alloy Cr-57.5Nb-5Si originated from the synergistic effects of precipitation strengthening, interface strengthening, solid solution strengthening, second phase toughening and alloying toughening.
Key words: Laves phase alloys; microstructures; mechanical properties; strengthening and toughening mechanisms
