Mg-8Sn-1Al-1Zn-xNi(x=0.5%, 1.0%, 1.5%, 2.0%, mass fraction) alloys were designed and prepared. The microstructures and the mechanical properties were studied by using optical microscope, scanning electronic microscope...Mg-8Sn-1Al-1Zn-xNi(x=0.5%, 1.0%, 1.5%, 2.0%, mass fraction) alloys were designed and prepared. The microstructures and the mechanical properties were studied by using optical microscope, scanning electronic microscope, energy dispersive X-ray spectroscope, X-ray diffraction and a standard universal testing machine. The results show that the microstructure of Ni-containing alloys consist of α-Mg, Mg2 Sn, β-Mg-Ni-Al and γ-AlNi phases. No β-Mg-Ni-Al phase was observed in TAZ811-2.0Ni alloy due to its 1:1 atomic ratio of Ni/Al. The addition of Ni refines the α-Mg dendrites and suppresses the formation of coarse Mg2 Sn phase. The tensile properties results show that the TAZ811-0.5Ni alloy presented the best mechanical properties, which is due to the rod-like β-Mg-Ni-Al phase, refined α-Mg dendrites and Mg2 Sn phase, as well as γ-AlNi phase. The tensile fracture mechanism transits from cleavage to quasi-cleavage fracture with the increasing Ni addition.展开更多
Thermal sprayed Ni-5wt.% Al coating was fabricated on the substrate of 6061-T6 aluminum alloy by twin-wire arc spraying. Experimental results indicated that the average value of bond strength was around 46. 90 MPa, th...Thermal sprayed Ni-5wt.% Al coating was fabricated on the substrate of 6061-T6 aluminum alloy by twin-wire arc spraying. Experimental results indicated that the average value of bond strength was around 46. 90 MPa, the average hardness was 240 HV and the average value of surface roughness was about O. 14 mm. Friction and wear test results showed that the dry friction coefficient of Ni-5wt.% Al coating firstly decreased, and then tended to a slight increase after 200 cycles. In the early abrasion stage, adhesion wear played the key role for wear mechanics of Ni-5wt.% Al coating, but gradually abrasive wear became to replace adhesion wear.展开更多
The oxidation behaviors of Ni-16Cr-xAl(x=4.5%, 9.0%, mass fraction) superalloy foams in air at 1 000 °C were investigated. The effects of Al content on the resistance to high temperature oxidation were examined. ...The oxidation behaviors of Ni-16Cr-xAl(x=4.5%, 9.0%, mass fraction) superalloy foams in air at 1 000 °C were investigated. The effects of Al content on the resistance to high temperature oxidation were examined. The oxidation mechanisms of the foams were discussed. The results show that the resistance to the oxidation of the Ni-16Cr-xAl based alloy at 1 000 °C increases with the content of Al increasing from 4.5% to 9.0%. Complex oxide products are formed on the surface of the superalloy foams after the oxidation. Cr2O3 and Al2O3 are the predominant oxides for the scales of the foams with 4.5% Al and 9% Al, respectively. Excellent high temperature oxidation resistance and superior pore conformation stability for the Ni-16Cr-xAl based superalloy foam with 9% Al can be mainly attributed to the formation of relatively continuous and protective Al2O3 oxides on the surface of the foam.展开更多
基金Projects supported by the Shanxi Selective Funds for Returned Scholars,ChinaProject(2013021013-4)supported by the Shanxi Province Science Foundation for Youths China+1 种基金Projects(2012L053,2012L003)supported by the Taiyuan University of Technology Funds for Young Scientists,ChinaProject(2014021017-2)supported by the Natural Science Foundation for Young Scientists for Shanxi Province,China
文摘Mg-8Sn-1Al-1Zn-xNi(x=0.5%, 1.0%, 1.5%, 2.0%, mass fraction) alloys were designed and prepared. The microstructures and the mechanical properties were studied by using optical microscope, scanning electronic microscope, energy dispersive X-ray spectroscope, X-ray diffraction and a standard universal testing machine. The results show that the microstructure of Ni-containing alloys consist of α-Mg, Mg2 Sn, β-Mg-Ni-Al and γ-AlNi phases. No β-Mg-Ni-Al phase was observed in TAZ811-2.0Ni alloy due to its 1:1 atomic ratio of Ni/Al. The addition of Ni refines the α-Mg dendrites and suppresses the formation of coarse Mg2 Sn phase. The tensile properties results show that the TAZ811-0.5Ni alloy presented the best mechanical properties, which is due to the rod-like β-Mg-Ni-Al phase, refined α-Mg dendrites and Mg2 Sn phase, as well as γ-AlNi phase. The tensile fracture mechanism transits from cleavage to quasi-cleavage fracture with the increasing Ni addition.
文摘Thermal sprayed Ni-5wt.% Al coating was fabricated on the substrate of 6061-T6 aluminum alloy by twin-wire arc spraying. Experimental results indicated that the average value of bond strength was around 46. 90 MPa, the average hardness was 240 HV and the average value of surface roughness was about O. 14 mm. Friction and wear test results showed that the dry friction coefficient of Ni-5wt.% Al coating firstly decreased, and then tended to a slight increase after 200 cycles. In the early abrasion stage, adhesion wear played the key role for wear mechanics of Ni-5wt.% Al coating, but gradually abrasive wear became to replace adhesion wear.
基金Project (51134003) supported by the National Natural Science Foundation of China
文摘The oxidation behaviors of Ni-16Cr-xAl(x=4.5%, 9.0%, mass fraction) superalloy foams in air at 1 000 °C were investigated. The effects of Al content on the resistance to high temperature oxidation were examined. The oxidation mechanisms of the foams were discussed. The results show that the resistance to the oxidation of the Ni-16Cr-xAl based alloy at 1 000 °C increases with the content of Al increasing from 4.5% to 9.0%. Complex oxide products are formed on the surface of the superalloy foams after the oxidation. Cr2O3 and Al2O3 are the predominant oxides for the scales of the foams with 4.5% Al and 9% Al, respectively. Excellent high temperature oxidation resistance and superior pore conformation stability for the Ni-16Cr-xAl based superalloy foam with 9% Al can be mainly attributed to the formation of relatively continuous and protective Al2O3 oxides on the surface of the foam.
