Two aluminum alloys,Al-8Zn and Al-6Bi-8Zn were subjected to equal channel angular pressing(ECAP)up to5passes at room temperature.The microstructural evolution and the grain refinement behavior of these alloys were sys...Two aluminum alloys,Al-8Zn and Al-6Bi-8Zn were subjected to equal channel angular pressing(ECAP)up to5passes at room temperature.The microstructural evolution and the grain refinement behavior of these alloys were systematically studied by electron backscatter diffraction(EBSD).After5passes of ECAP,ultrafine grained microstructures formed in both alloys.However,the grain structure in the Al-6Bi-8Zn alloy is much finer than that of Al-8Zn alloy,showing that the soft Bi particles have a strong influence on enhancing the grain refinement during ECAP.The strengths of the ECAP-processed materials were measured by hardness test and it showed that after5passes of ECAP,the hardness of the Al-6Bi-8Zn alloy was higher than that of the Al-8Zn alloy.The effects of soft Bi particles on the deformation behavior during ECAP and the final strength of the Al-6Bi-8Zn alloy were discussed.展开更多
As-cast samples of the Al-3wt.%Ni-lwt.%Bi alloy resulting from the horizontal directional solidification process were subjected to the micro-abrasive wear test.The effects of the solidification thermal and microstruct...As-cast samples of the Al-3wt.%Ni-lwt.%Bi alloy resulting from the horizontal directional solidification process were subjected to the micro-abrasive wear test.The effects of the solidification thermal and microstructural parameters,such as the growth and cooling rates and the cellular and primary dendritic spacings(VL and TR;λ1 and λc;respectively),were evaluated in the wear resistance of the investigated alloy.The tribological parameters analyzed were the wear volume and rate(Vw and Rw).The solidification experiments and the wear tests were carried out by means of a water-cooled horizontal directional solidification device and a rotary-fixed ball wear machine,respectively.The results show lower Vw and Rw values correspond to finer microstructures and the Vw dependence on λ1 is characterized by an experimental mathematical equation.A better distribution of Bi soft droplets and Al3Ni hard intermetallic particles is observed within the finer interdendritic region and,in consequence,the better wear resistance is achieved in as-cast samples with dendritic morphology rather than cellular morphology.A transition of wear mechanism from adhesive to abrasive is observed.展开更多
基金Project(10407002)supported by Research Council of NorwayProject(201406080011)supported by China Scholarship Council
文摘Two aluminum alloys,Al-8Zn and Al-6Bi-8Zn were subjected to equal channel angular pressing(ECAP)up to5passes at room temperature.The microstructural evolution and the grain refinement behavior of these alloys were systematically studied by electron backscatter diffraction(EBSD).After5passes of ECAP,ultrafine grained microstructures formed in both alloys.However,the grain structure in the Al-6Bi-8Zn alloy is much finer than that of Al-8Zn alloy,showing that the soft Bi particles have a strong influence on enhancing the grain refinement during ECAP.The strengths of the ECAP-processed materials were measured by hardness test and it showed that after5passes of ECAP,the hardness of the Al-6Bi-8Zn alloy was higher than that of the Al-8Zn alloy.The effects of soft Bi particles on the deformation behavior during ECAP and the final strength of the Al-6Bi-8Zn alloy were discussed.
基金financial support provided by IFPA-Federal Institute of Education, Science and Technology of Pará, UFPA-Federal University of Pará, and CNPq-The Brazilian Research Council (grants 302846/2017-4 and 400634/2016-3)CAPES-Coordenacao de Aperfeicoamento de Pessoal de Nível SuperiorBrasil-Finance Code 001
文摘As-cast samples of the Al-3wt.%Ni-lwt.%Bi alloy resulting from the horizontal directional solidification process were subjected to the micro-abrasive wear test.The effects of the solidification thermal and microstructural parameters,such as the growth and cooling rates and the cellular and primary dendritic spacings(VL and TR;λ1 and λc;respectively),were evaluated in the wear resistance of the investigated alloy.The tribological parameters analyzed were the wear volume and rate(Vw and Rw).The solidification experiments and the wear tests were carried out by means of a water-cooled horizontal directional solidification device and a rotary-fixed ball wear machine,respectively.The results show lower Vw and Rw values correspond to finer microstructures and the Vw dependence on λ1 is characterized by an experimental mathematical equation.A better distribution of Bi soft droplets and Al3Ni hard intermetallic particles is observed within the finer interdendritic region and,in consequence,the better wear resistance is achieved in as-cast samples with dendritic morphology rather than cellular morphology.A transition of wear mechanism from adhesive to abrasive is observed.
