Ultrafine-grained commercial-purity aluminum（AA1070） sheets produced by four cycles of accumulative roll-bonding（ARB） without lubrication are subjected to annealing treatments in the temperature range from 250℃ t...Ultrafine-grained commercial-purity aluminum（AA1070） sheets produced by four cycles of accumulative roll-bonding（ARB） without lubrication are subjected to annealing treatments in the temperature range from 250℃ to 400℃.Microstructures and microtextures in the surface and center regions of the ARBed and annealed sheets are measured by electron backscatter diffraction.The results show that annealing treatments at 325℃ or above lead to a reduction in the microstructure gradient but a significant through-thickness texture gradient different from that in the as-deformed state.The center region is featured by the development of a strong cube texture at the expense of rolling components.In the surface region,shear-type components are either enhanced or largely retained,showing a high persistency upon annealing.While the grain structures are restored predominantly by continuous recrystallization in the surface region,a mixture of continuous and discontinuous recrystallization is envisaged for the center region.展开更多
In the present investigation a wrought magnesium alloy AZ31 was successfully processed by the accumulative roll-bonding （ARB） at gradient temperature up to six cycles with the lowest temperature of 250 °C. This...In the present investigation a wrought magnesium alloy AZ31 was successfully processed by the accumulative roll-bonding （ARB） at gradient temperature up to six cycles with the lowest temperature of 250 °C. This is performed through different thermomechanical processing routes （different ARB cycles at different temperatures of 350-200 °C）. The microstructures and mechanical properties were investigated. The results indicate that significant grain refinement is observed after the first two cycles at the highest ARB temperature as a result of dynamic recrystallization, which is necessary for the subsequently ARB cycles at relatively lower temperature with the aim to restrict grain growth. No significant finer grain size was observed through the fifth and sixth cycles while the microstructure homogeneity is further improved. The grain structure can be effectively refined at lower ARB processing temperature and higher cycles. The resulting material exhibited high strength and relatively high ductility at ambient temperature when ARB deformed above 250 °C. The mechanical properties of the ARB deformed materials are strongly dependent on several main factors： the amount and the homogeneity of strain achieved, grain size and microstructure homogeneity, textures developed during ARB and interface bonding quality.展开更多
Nano structured Cu-/Al-laminated composites were processed by accumulative roll-bonding(ARB)technique for four cycles.Microstructural evolutions inside the Cu and Al layers and the interfacial reactions were revealed ...Nano structured Cu-/Al-laminated composites were processed by accumulative roll-bonding(ARB)technique for four cycles.Microstructural evolutions inside the Cu and Al layers and the interfacial reactions were revealed after annealing at different temperatures.Recovery and recrystallization occurred in the Cu and Al layers at low annealing temperatures,and three kinds of intermetallic compounds formed near the interfaces.The mechanical properties of these composites after annealing were investigated by tensile tests,and the variation of strength-ductility synergy was comprehensively discussed by considering the roles of constituent and the intermetallic compounds.展开更多
基金supported by the National Natural Science Foundation of China (Nos.51571213 and 51271204)the Hunan Provincial Innovation Foundation for Postgraduate (No.CX2016B040)
文摘Ultrafine-grained commercial-purity aluminum（AA1070） sheets produced by four cycles of accumulative roll-bonding（ARB） without lubrication are subjected to annealing treatments in the temperature range from 250℃ to 400℃.Microstructures and microtextures in the surface and center regions of the ARBed and annealed sheets are measured by electron backscatter diffraction.The results show that annealing treatments at 325℃ or above lead to a reduction in the microstructure gradient but a significant through-thickness texture gradient different from that in the as-deformed state.The center region is featured by the development of a strong cube texture at the expense of rolling components.In the surface region,shear-type components are either enhanced or largely retained,showing a high persistency upon annealing.While the grain structures are restored predominantly by continuous recrystallization in the surface region,a mixture of continuous and discontinuous recrystallization is envisaged for the center region.
基金supported by the National Natural Science Foundation of China(No.50801027)Public Foundation of Guangdong Key Laboratory for Advanced Metallic Materials Processing, South China University of Technology, China(No.2007001)
文摘In the present investigation a wrought magnesium alloy AZ31 was successfully processed by the accumulative roll-bonding （ARB） at gradient temperature up to six cycles with the lowest temperature of 250 °C. This is performed through different thermomechanical processing routes （different ARB cycles at different temperatures of 350-200 °C）. The microstructures and mechanical properties were investigated. The results indicate that significant grain refinement is observed after the first two cycles at the highest ARB temperature as a result of dynamic recrystallization, which is necessary for the subsequently ARB cycles at relatively lower temperature with the aim to restrict grain growth. No significant finer grain size was observed through the fifth and sixth cycles while the microstructure homogeneity is further improved. The grain structure can be effectively refined at lower ARB processing temperature and higher cycles. The resulting material exhibited high strength and relatively high ductility at ambient temperature when ARB deformed above 250 °C. The mechanical properties of the ARB deformed materials are strongly dependent on several main factors： the amount and the homogeneity of strain achieved, grain size and microstructure homogeneity, textures developed during ARB and interface bonding quality.
基金financially supported by the Fundamental Research Funds for the Central Universities under grant No.N180204015the National Natural Science Foundation of China(NSFC)under Grant No.51331007。
文摘Nano structured Cu-/Al-laminated composites were processed by accumulative roll-bonding(ARB)technique for four cycles.Microstructural evolutions inside the Cu and Al layers and the interfacial reactions were revealed after annealing at different temperatures.Recovery and recrystallization occurred in the Cu and Al layers at low annealing temperatures,and three kinds of intermetallic compounds formed near the interfaces.The mechanical properties of these composites after annealing were investigated by tensile tests,and the variation of strength-ductility synergy was comprehensively discussed by considering the roles of constituent and the intermetallic compounds.
