Cast ZM21 magnesium alloys were subjected to symmetric extrusion at four different temperatures（200,250,300 and 350 ℃） with three extrusion ratios of 4：1,9：1 and 16：1,respectively.The effects of extrusion parame...Cast ZM21 magnesium alloys were subjected to symmetric extrusion at four different temperatures（200,250,300 and 350 ℃） with three extrusion ratios of 4：1,9：1 and 16：1,respectively.The effects of extrusion parameters such as temperature and extrusion ratio were studied by optical microscopy,X-ray diffraction（XRD） and tensile test.The optical micrographs exhibited various stages of recrystallization,i.e.,partial to full recrystallization influencing mechanical properties to good extent.Higher extrusion temperature resulted in coarse grains,whereas finer grains were obtained at higher extrusion ratios.Ultimate tensile strength of this alloy was increased from 160 MPa to 316 MPa after extrusion at 250 ℃ with an extrusion ratio of 9：1.展开更多
The single-phase Mg-4Li-0.5Ca alloy was rolled at three different temperatures(250,300 and 350℃)and followed by annealing at 200°C for 10 min.To evaluate the mechanical properties,the tensile test was conducted ...The single-phase Mg-4Li-0.5Ca alloy was rolled at three different temperatures(250,300 and 350℃)and followed by annealing at 200°C for 10 min.To evaluate the mechanical properties,the tensile test was conducted at a constant strain rate of 10^(-3)s^(-1).Factors influencing the tensile strength and strain hardening properties were assessed by microscopy,XRD and EBSD analysis.Besides,Kocks-Mecking plots(K-M)were used to determine the different stages of strain hardening exhibited by the variously processed Mg-4Li-0.5Ca alloy test specimens.The ultimate tensile strength has decreased as hot-rolling temperature in creases with increased ductility.The strain hardening properties such as hardening capacity(Hc),strain hardening exponent(n)are increased significantly with an increase in hot rolling temperature and subsequent annealing.展开更多
Al-12Zn-3Mg-2.5Cu alloy was prepared using a liquid metallurgy route under the optimized conditions. A sample cut from the ingot was rolled non-isothermally from 400℃ to 100℃ in 100℃ steps, with 15% reduction in th...Al-12Zn-3Mg-2.5Cu alloy was prepared using a liquid metallurgy route under the optimized conditions. A sample cut from the ingot was rolled non-isothermally from 400℃ to 100℃ in 100℃ steps, with 15% reduction in thickness; it was then cold rolled isothermally at room temperature for 85% reduction. The cold-rolled alloys were characterized by electron microscopy, hardness test, and tensile test to elucidate their structural evolution and evaluate their mechanical behavior. In the results, the cast alloy consists of a-aluminum and various intermetallic compounds. These compounds are segregated along the grain boundaries, which makes the alloy difficult to roll at room tem- perature. The combined effect of non-isothermal step rolling and cold rolling results in the nano/microsized compounds distributed uniformly in the matrix. The hardness is substantially increased after rolling. This increase in hardness is attributed to the ultra-fine grain size, fine-scale intermetallic compounds, and structural defects （e.g., dislocations, stacking faults, and sub-grains）. The ultimate tensile strength of the rolled alloy is approximately 628 MPa with 7% ductility.展开更多
文摘Cast ZM21 magnesium alloys were subjected to symmetric extrusion at four different temperatures（200,250,300 and 350 ℃） with three extrusion ratios of 4：1,9：1 and 16：1,respectively.The effects of extrusion parameters such as temperature and extrusion ratio were studied by optical microscopy,X-ray diffraction（XRD） and tensile test.The optical micrographs exhibited various stages of recrystallization,i.e.,partial to full recrystallization influencing mechanical properties to good extent.Higher extrusion temperature resulted in coarse grains,whereas finer grains were obtained at higher extrusion ratios.Ultimate tensile strength of this alloy was increased from 160 MPa to 316 MPa after extrusion at 250 ℃ with an extrusion ratio of 9：1.
文摘The single-phase Mg-4Li-0.5Ca alloy was rolled at three different temperatures(250,300 and 350℃)and followed by annealing at 200°C for 10 min.To evaluate the mechanical properties,the tensile test was conducted at a constant strain rate of 10^(-3)s^(-1).Factors influencing the tensile strength and strain hardening properties were assessed by microscopy,XRD and EBSD analysis.Besides,Kocks-Mecking plots(K-M)were used to determine the different stages of strain hardening exhibited by the variously processed Mg-4Li-0.5Ca alloy test specimens.The ultimate tensile strength has decreased as hot-rolling temperature in creases with increased ductility.The strain hardening properties such as hardening capacity(Hc),strain hardening exponent(n)are increased significantly with an increase in hot rolling temperature and subsequent annealing.
文摘Al-12Zn-3Mg-2.5Cu alloy was prepared using a liquid metallurgy route under the optimized conditions. A sample cut from the ingot was rolled non-isothermally from 400℃ to 100℃ in 100℃ steps, with 15% reduction in thickness; it was then cold rolled isothermally at room temperature for 85% reduction. The cold-rolled alloys were characterized by electron microscopy, hardness test, and tensile test to elucidate their structural evolution and evaluate their mechanical behavior. In the results, the cast alloy consists of a-aluminum and various intermetallic compounds. These compounds are segregated along the grain boundaries, which makes the alloy difficult to roll at room tem- perature. The combined effect of non-isothermal step rolling and cold rolling results in the nano/microsized compounds distributed uniformly in the matrix. The hardness is substantially increased after rolling. This increase in hardness is attributed to the ultra-fine grain size, fine-scale intermetallic compounds, and structural defects （e.g., dislocations, stacking faults, and sub-grains）. The ultimate tensile strength of the rolled alloy is approximately 628 MPa with 7% ductility.
