The microstructures and mechanical properties were systematically studied for the high-strength Al−5Mg_(2)Si−1.5Ni alloy fabricated by laser powder bed fusion(L-PBF).It is found that the introduction of Ni(1.5 wt.%)in...The microstructures and mechanical properties were systematically studied for the high-strength Al−5Mg_(2)Si−1.5Ni alloy fabricated by laser powder bed fusion(L-PBF).It is found that the introduction of Ni(1.5 wt.%)into an Al−5Mg_(2)Si alloy can significantly improve the L-PBF processibility and provide remarkable improvement in mechanical properties.The solidification range of just 85.5 K and the typical Al−Al3Ni eutectics could be obtained in the Ni-modified Al−5Mg_(2)Si samples with a high relative density of 99.8%at the volumetric energy density of 107.4 J/mm^(3).Additionally,the refined hierarchical microstructure was mainly characterized by heterogeneousα-Al matrix grains(14.6μm)that contain the interaction between dislocations and Al−Al3Ni eutectics as well as Mg_(2)Si particles.Through synergetic effects of grain refinement,dislocation strengthening and precipitation strengthening induced by Ni addition,the L-PBFed Al−5Mg_(2)Si−1.5Ni alloy achieved superior mechanical properties,which included the yield strength of(425±15)MPa,the ultimate tensile strength of(541±11)MPa and the elongation of(6.2±0.2)%.展开更多
The microstructures and mechanical properties of Mg-6Zn-1Mn-4Sn and Mg-6Zn-1Mn-4Sn-0.5Y alloys under extrusion and T6 aging conditions were investigated by optical microscopy（OM）, X-ray diffraction（XRD）, scanning ...The microstructures and mechanical properties of Mg-6Zn-1Mn-4Sn and Mg-6Zn-1Mn-4Sn-0.5Y alloys under extrusion and T6 aging conditions were investigated by optical microscopy（OM）, X-ray diffraction（XRD）, scanning electron microscopy（SEM） and tensile test. The results show that Y element refines the grains and improves the comprehensive mechanical properties of ZMT614-0.5Y both in as-extruded and T6 states. The phase compositions of Mg-6Zn-1Mn-4Sn-0.5Y are α-Mg, Mg Zn2, Mn, Mg2 Sn and Mg Sn Y phases. After T6 treatment, the ultimate tensile strength（UTS） and yield strength（YS） increase while the elongation decreases severely. For both of these alloys, the theoretical results combined with the experimental values demonstrate that the grain boundary strengthening and solid solution strengthening play an important role in enhancing the YS in the as-extruded state, while the precipitation strengthening is the key factor for the enhancement of YS in the T6 state.展开更多
The precipitation hardening behavior in dilute Al-Yb alloys upon annealing at different temperatures was investigated to shed light on the mechanism of micro-alloying element in aluminum alloys. When aging at differen...The precipitation hardening behavior in dilute Al-Yb alloys upon annealing at different temperatures was investigated to shed light on the mechanism of micro-alloying element in aluminum alloys. When aging at different temperatures, the samples showed their corresponding peak hardness in the range of 400-416 MPa due to the precipitation of Al3Yb with L 12 crystal structure. The coarsening kinetics of the Al3Yb precipitates obeyed the LSW theory, which indicated that the coarsening process was controlled by the diffusion of Yb. The coherence between Al3Yb particles and matrix was maintained until the particle size reached 11 nm. When the particle size increased to about 2 nm, the shearing mechanism started to change to Orowan mechanism.展开更多
Microstructure and texture evolution of Cu-0.23%Al2O3 dispersion strengthened copper alloy, deformed at room temperature or cryogenic temperature, were investigated. The main textures in hot-extruded specimen were Bra...Microstructure and texture evolution of Cu-0.23%Al2O3 dispersion strengthened copper alloy, deformed at room temperature or cryogenic temperature, were investigated. The main textures in hot-extruded specimen were Brass {011} 〈211〉 and Cube {100} 〈100〉. Textures of Brass {011} 〈211〉 and Goss {011} 〈100〉 were observed in specimen after deformation at room temperature; while textures of Brass {011} 〈211〉, Goss {011} 〈100〉 and S {123} 〈634〉 were detected after deformation at cryogenic temperature. It is believed that the additional Al2O3 nanoparticles can result in dislocation pinning effect, which can further lead to the suppression of dislocations cross-slip. While in the specimen deformed at cryogenic temperature, both pinning effect and cryogenic temperature are responsible for the formation of Brass, Goss and S textures.展开更多
The microstructure, age hardening behavior and mechanical properties of an Mg-8.5Gd-2.3Y-1.8Ag-0.4Zr alloy prepared by casting and hot extrusion techniques were investigated. The solution-treated （T4 temper） alloys ...The microstructure, age hardening behavior and mechanical properties of an Mg-8.5Gd-2.3Y-1.8Ag-0.4Zr alloy prepared by casting and hot extrusion techniques were investigated. The solution-treated （T4 temper） alloys were extruded at 400, 450 and 500 °C with an extrusion ratio of 10：1, respectively. Optimized mechanical properties were obtained by extrusion at 400 °C followed by T5 treatment under the combined effects of grain refinement and precipitation strengthening. The alloy exhibits a grain size of about 5.0 μm, initial and peak microhardness of HV 109 and HV 129, respectively. The tensile yield strength, ultimate tensile strength and elongation at room temperature are 391 MPa, 430 MPa and 5.2%, respectively.展开更多
基金Financial supports from the National Natural Science Foundation of China (No.52071343)the Leading Innovation and Entrepreneurship Team of Zhejiang Province,China—Automotive Light Alloy Innovation Team (No.2022R01018)are gratefully acknowledged。
文摘The microstructures and mechanical properties were systematically studied for the high-strength Al−5Mg_(2)Si−1.5Ni alloy fabricated by laser powder bed fusion(L-PBF).It is found that the introduction of Ni(1.5 wt.%)into an Al−5Mg_(2)Si alloy can significantly improve the L-PBF processibility and provide remarkable improvement in mechanical properties.The solidification range of just 85.5 K and the typical Al−Al3Ni eutectics could be obtained in the Ni-modified Al−5Mg_(2)Si samples with a high relative density of 99.8%at the volumetric energy density of 107.4 J/mm^(3).Additionally,the refined hierarchical microstructure was mainly characterized by heterogeneousα-Al matrix grains(14.6μm)that contain the interaction between dislocations and Al−Al3Ni eutectics as well as Mg_(2)Si particles.Through synergetic effects of grain refinement,dislocation strengthening and precipitation strengthening induced by Ni addition,the L-PBFed Al−5Mg_(2)Si−1.5Ni alloy achieved superior mechanical properties,which included the yield strength of(425±15)MPa,the ultimate tensile strength of(541±11)MPa and the elongation of(6.2±0.2)%.
基金Project(2013CB632200)supported by National Basic Research Program of ChinaProject(2010DFR50010)supported by International Scientific and Technological Cooperation Program of Ministry of Science and Technology of ChinaProject supported by Sharing Fund of Chongqing University’s Large-scale Equipment,China
文摘The microstructures and mechanical properties of Mg-6Zn-1Mn-4Sn and Mg-6Zn-1Mn-4Sn-0.5Y alloys under extrusion and T6 aging conditions were investigated by optical microscopy（OM）, X-ray diffraction（XRD）, scanning electron microscopy（SEM） and tensile test. The results show that Y element refines the grains and improves the comprehensive mechanical properties of ZMT614-0.5Y both in as-extruded and T6 states. The phase compositions of Mg-6Zn-1Mn-4Sn-0.5Y are α-Mg, Mg Zn2, Mn, Mg2 Sn and Mg Sn Y phases. After T6 treatment, the ultimate tensile strength（UTS） and yield strength（YS） increase while the elongation decreases severely. For both of these alloys, the theoretical results combined with the experimental values demonstrate that the grain boundary strengthening and solid solution strengthening play an important role in enhancing the YS in the as-extruded state, while the precipitation strengthening is the key factor for the enhancement of YS in the T6 state.
基金Project(2013AA031301)supported by Hi-tech Research and Development Program of ChinaProject(S2013ZR0611)supported by the National International Scientific and Technological Cooperation Program of China
文摘The precipitation hardening behavior in dilute Al-Yb alloys upon annealing at different temperatures was investigated to shed light on the mechanism of micro-alloying element in aluminum alloys. When aging at different temperatures, the samples showed their corresponding peak hardness in the range of 400-416 MPa due to the precipitation of Al3Yb with L 12 crystal structure. The coarsening kinetics of the Al3Yb precipitates obeyed the LSW theory, which indicated that the coarsening process was controlled by the diffusion of Yb. The coherence between Al3Yb particles and matrix was maintained until the particle size reached 11 nm. When the particle size increased to about 2 nm, the shearing mechanism started to change to Orowan mechanism.
基金Project(51271203)supported by the National Natural Science Foundation of ChinaProject(YSZN2013CLD6)supported by the Nonferrous Metals Science Foundation of HNG-CSU+1 种基金ChinaProject supported by the Program Between the CSC(China Scholarship Council)and the DAAD(German Academic Exchange Service)
文摘Microstructure and texture evolution of Cu-0.23%Al2O3 dispersion strengthened copper alloy, deformed at room temperature or cryogenic temperature, were investigated. The main textures in hot-extruded specimen were Brass {011} 〈211〉 and Cube {100} 〈100〉. Textures of Brass {011} 〈211〉 and Goss {011} 〈100〉 were observed in specimen after deformation at room temperature; while textures of Brass {011} 〈211〉, Goss {011} 〈100〉 and S {123} 〈634〉 were detected after deformation at cryogenic temperature. It is believed that the additional Al2O3 nanoparticles can result in dislocation pinning effect, which can further lead to the suppression of dislocations cross-slip. While in the specimen deformed at cryogenic temperature, both pinning effect and cryogenic temperature are responsible for the formation of Brass, Goss and S textures.
基金Projects (50674067, 51074106) supported by the National Natural Science Foundation of ChinaProject (2009AA033501) supported by the High-Tech Research and Development Program of ChinaProject (09JC1408200) supported by the Science and Technology Commission of Shanghai Municipality, China
文摘The microstructure, age hardening behavior and mechanical properties of an Mg-8.5Gd-2.3Y-1.8Ag-0.4Zr alloy prepared by casting and hot extrusion techniques were investigated. The solution-treated （T4 temper） alloys were extruded at 400, 450 and 500 °C with an extrusion ratio of 10：1, respectively. Optimized mechanical properties were obtained by extrusion at 400 °C followed by T5 treatment under the combined effects of grain refinement and precipitation strengthening. The alloy exhibits a grain size of about 5.0 μm, initial and peak microhardness of HV 109 and HV 129, respectively. The tensile yield strength, ultimate tensile strength and elongation at room temperature are 391 MPa, 430 MPa and 5.2%, respectively.
