The aluminum matrix composites(AlB2+a-Al2O3)/Al were fabricated by in situ reaction synthesis from an Al-B2 O3 system. The reaction pathways, apparent activation energies and tensile properties were analyzed by using ...The aluminum matrix composites(AlB2+a-Al2O3)/Al were fabricated by in situ reaction synthesis from an Al-B2 O3 system. The reaction pathways, apparent activation energies and tensile properties were analyzed by using differential scanning calorimetry(DSC), X-ray diffraction(XRD), scanning electron microscopy(SEM), and equipped energy dispersive spectroscopy(EDS). The results showed that there are two-step reactions in the Al-B2 O3 system. The first-step is 15 Al+7 B2 O3→7 aAl2O3+AlB12+2 B and the second-step is 2 B+AlB12+6 Al→7 AlB2. Their corresponding apparent activation energies are 352 and 444 kJ/mol, respectively. The tensile strength and elongation rate of the composites are 190.5 MPa and 6.6%, respectively.Compared with ordinary aluminum base material, the performance is superior. There are many dimple and cracked a-Al2O3 reinforcements in tensile fracture surface layer.展开更多
Five sets of high entropy alloys(HEAs)FeCoNiCu_(x)(x=0.5,1.0,1.5,2.0,2.5)were produced by vacuum induction smelting.The effects of Cu content on the microstructure and mechanical properties of the alloys were interrog...Five sets of high entropy alloys(HEAs)FeCoNiCu_(x)(x=0.5,1.0,1.5,2.0,2.5)were produced by vacuum induction smelting.The effects of Cu content on the microstructure and mechanical properties of the alloys were interrogated by X-ray diffractometer(XRD),field scanning electron microscope(FESEM)and tensile mechanical test.The result shows that the HEAs form single FCC solid solution phase.With the increase of Cu content,the diffraction peak first deviated to the right and then shifted to the left.The alloys changed from equiaxed crystal structure to refined dendritic crystal structure,as Cu content increased.A large number of Cu atoms are isolated in the inter-crystalline region.The tensile mechanical tests show that with the increase of Cu content,the ultimate tensile strength first increased and then decreased.When x is 2.0,the ultimate tensile strength reaches a maximum of 473 MPa,the percent elongation is 43.0%,and the fracture presents ductile behaviour.展开更多
基金Supported by the National Natural Science Foundation of China(Nos.51571118 and 51371098)Natural Science Foundation of Jiangsu Province(No.BK20141308)
文摘The aluminum matrix composites(AlB2+a-Al2O3)/Al were fabricated by in situ reaction synthesis from an Al-B2 O3 system. The reaction pathways, apparent activation energies and tensile properties were analyzed by using differential scanning calorimetry(DSC), X-ray diffraction(XRD), scanning electron microscopy(SEM), and equipped energy dispersive spectroscopy(EDS). The results showed that there are two-step reactions in the Al-B2 O3 system. The first-step is 15 Al+7 B2 O3→7 aAl2O3+AlB12+2 B and the second-step is 2 B+AlB12+6 Al→7 AlB2. Their corresponding apparent activation energies are 352 and 444 kJ/mol, respectively. The tensile strength and elongation rate of the composites are 190.5 MPa and 6.6%, respectively.Compared with ordinary aluminum base material, the performance is superior. There are many dimple and cracked a-Al2O3 reinforcements in tensile fracture surface layer.
基金Funded by the National Natural Science Foundation of China(Nos.51371098,51571118)National Undergraduate Training Program for Innovation and Entrepreneurship(No.201910288094Z)。
文摘Five sets of high entropy alloys(HEAs)FeCoNiCu_(x)(x=0.5,1.0,1.5,2.0,2.5)were produced by vacuum induction smelting.The effects of Cu content on the microstructure and mechanical properties of the alloys were interrogated by X-ray diffractometer(XRD),field scanning electron microscope(FESEM)and tensile mechanical test.The result shows that the HEAs form single FCC solid solution phase.With the increase of Cu content,the diffraction peak first deviated to the right and then shifted to the left.The alloys changed from equiaxed crystal structure to refined dendritic crystal structure,as Cu content increased.A large number of Cu atoms are isolated in the inter-crystalline region.The tensile mechanical tests show that with the increase of Cu content,the ultimate tensile strength first increased and then decreased.When x is 2.0,the ultimate tensile strength reaches a maximum of 473 MPa,the percent elongation is 43.0%,and the fracture presents ductile behaviour.
基金Science and Technology Advancement Project in Jiangsu Province(BE2018753/KJ185629)National Natural Science Foundation of China(51571118,51371098)2020 Extracurricular Academic Research Fund for College Students of Nanjing University of Science and Technology。
