用固态扩散方法实现了CoCrFeMnNi高熵合金与铜在温度750~850℃下的良好连接,利用扫描电镜(Scanning electron microscope,SEM)、能谱(Energy disperse spectroscopy,EDS)分析、显微硬度测试及拉伸试验研究扩散反应温度对其界面反应行为...用固态扩散方法实现了CoCrFeMnNi高熵合金与铜在温度750~850℃下的良好连接,利用扫描电镜(Scanning electron microscope,SEM)、能谱(Energy disperse spectroscopy,EDS)分析、显微硬度测试及拉伸试验研究扩散反应温度对其界面反应行为和接头力学性能的影响,结合菲克扩散第二定律计算和分析Cu原子在高熵合金中的扩散系数。结果表明:Cu在高熵合金一侧的扩散速率大于高熵合金组元在Cu侧的扩散,随温度增加,高熵合金组元向Cu侧扩散时其在扩散区内原子浓度分布降低的程度按Mn>Cr>Fe>Co>Ni的顺序依次减小。理论计算表明,Cu在高熵合金中的平均扩散系数明显小于铜在不锈钢中的平均扩散系数。经扩散反应后,Cu/高熵合金界面附近均可形成FCC型固溶体组织的反应层,无金属间化合物产生。所有扩散连接接头拉伸后其断裂均发生在远离界面的铜侧,随扩散焊温度升高,其抗拉强度和应变有所降低,其中750℃时铜的抗拉强度与应变分别达到最大值224MPa和33%。展开更多
Diffusion bonding of TC21 titanium alloy was carried out at temperature ranging from 780 ℃ to 980 ℃ for 5-90 min.The interfacial bonding ratio,deformation ratio,microstructures and microhardness of the diffusion bon...Diffusion bonding of TC21 titanium alloy was carried out at temperature ranging from 780 ℃ to 980 ℃ for 5-90 min.The interfacial bonding ratio,deformation ratio,microstructures and microhardness of the diffusion bonded joints were investigated.Results show that joints with high bonding quality can be obtained when bonded at 880 ℃ for 15？30 min.The microhardness increases with increasing the bonding temperature,while it has a peak value（HV367） when bonding time is prolonged up to 90 min.Fully equiaxed microstructures,bi-modal microstructures and fully lamellar microstructures were observed when bonded in temperature range of 780-880 ℃,at 930 ℃ or 980 ℃,respectively.The volume fraction of α phase first increases and achieves the maximum when bonded at 880 ℃ for 60 min,and then descended.展开更多
The ultra high strength SiC particles （SiCp） reinforced Al-10%Zn-3.6%Mg-1.8%Cu-0.36%Zr-0.15% Ni composite was prepared by spray co-deposition. Microstructures of the extruded and different heat-treated bars were ana...The ultra high strength SiC particles （SiCp） reinforced Al-10%Zn-3.6%Mg-1.8%Cu-0.36%Zr-0.15% Ni composite was prepared by spray co-deposition. Microstructures of the extruded and different heat-treated bars were analyzed by transmission electron microscopy （TEM） and energy dispersive spectrometry （EDS）. Grain size of the composites prepared by two-stage solution is smaller than that by single-stage solution. After single-stage solution aging treatment, fine precipitates of both η and AlZnMgCu-rich phase can be found both intragranularly and intergranularly. While after the two-stage solution, an amorphous Si-Cu-Al-O （5 nm） layer appears at the interface. The addition of Ni and Zr modified the influence of the two-stage solution and inhibited the growth of the 7090/SiCp composite grain size. Heat treatments can significantly improve the fracture toughness of the composite. The fracture toughness first decreases then increases with the elongation of the aging time.展开更多
Based on the diffusion channel,the influence of Si content on the microstructure evolution of iron-based hot-dip Al-χSi coating was analyzed(χ=0,1.5 wt%,3.0 wt% and 7.0 wt%).The results show that the introduction of...Based on the diffusion channel,the influence of Si content on the microstructure evolution of iron-based hot-dip Al-χSi coating was analyzed(χ=0,1.5 wt%,3.0 wt% and 7.0 wt%).The results show that the introduction of Si makes the reaction interface change from the lingual-tooth interface of hot-dip Al to the flat interface of hot-dip Al-Si.It also reduces the thickness of the alloy layer in the coating,especially the Fe_(2)Al_(5) layer.When the Si content is 1.5 wt%or 3.0 wt%,the diffusion channel crosses the conjugate line of the two-phase region(FeAl_(3)+liquid phase)into the FeAl_(3) single-phase region,and then moves to the region with higher Si content.Next,the diffusion channel cuts off the conjugate line of FeAl_(3)phase,τ_(1)/τ_(9) phase,and Fe_(2)Al_(5)phase,which promotes the form ofτ_(1)/τ_(9) phase.The formedτ_(1)/τ_(9) phase inhibits the diffusion between Fe and Al atoms.When the Si content is 7.0 wt%,the diffusion channel passes through the two-phase region(liquid phase+τ_(5))and enters theτ_(5) single-phase region.The form ofτ_(5) single-phase region has a strong inhibitory effect on the interatomic diffusion of Fe and Al,thereby reducing the thickness of the coating,especially the Fe_(2)Al_(5)layer.展开更多
Similar friction welded joints of AA-7005 aluminum rods were fabricated using different combinations of process parameters such as friction pressure(1.0, 1.5 and 2.0 MPa) and friction time(10, 15 and 20 s). Interfacia...Similar friction welded joints of AA-7005 aluminum rods were fabricated using different combinations of process parameters such as friction pressure(1.0, 1.5 and 2.0 MPa) and friction time(10, 15 and 20 s). Interfacial microstructure and formation of intermetallic compounds at the joint interface were evaluated via scanning electron microscopy(SEM) equipped with energy dispersive spectrum(EDS), and optical microscopy(OM). Microstructural observations reveal the formation of intermetallic phases during the welding process which cannot be extruded from the interface. Theses phases influence the tensile strength of the resultant joints. From the tensile characteristics viewpoint, the greatest tensile strength value of 365 MPa is obtained at 1.5 MPa and 15 s. Finally, the role of microstructural features on tensile strength of resultant joints is discussed.展开更多
文摘用固态扩散方法实现了CoCrFeMnNi高熵合金与铜在温度750~850℃下的良好连接,利用扫描电镜(Scanning electron microscope,SEM)、能谱(Energy disperse spectroscopy,EDS)分析、显微硬度测试及拉伸试验研究扩散反应温度对其界面反应行为和接头力学性能的影响,结合菲克扩散第二定律计算和分析Cu原子在高熵合金中的扩散系数。结果表明:Cu在高熵合金一侧的扩散速率大于高熵合金组元在Cu侧的扩散,随温度增加,高熵合金组元向Cu侧扩散时其在扩散区内原子浓度分布降低的程度按Mn>Cr>Fe>Co>Ni的顺序依次减小。理论计算表明,Cu在高熵合金中的平均扩散系数明显小于铜在不锈钢中的平均扩散系数。经扩散反应后,Cu/高熵合金界面附近均可形成FCC型固溶体组织的反应层,无金属间化合物产生。所有扩散连接接头拉伸后其断裂均发生在远离界面的铜侧,随扩散焊温度升高,其抗拉强度和应变有所降低,其中750℃时铜的抗拉强度与应变分别达到最大值224MPa和33%。
基金Project(2010CB731704)supported by the National Basic Research Program of Chinathe Northwest Institute for Non-ferrous Metal Research of China for the support
文摘Diffusion bonding of TC21 titanium alloy was carried out at temperature ranging from 780 ℃ to 980 ℃ for 5-90 min.The interfacial bonding ratio,deformation ratio,microstructures and microhardness of the diffusion bonded joints were investigated.Results show that joints with high bonding quality can be obtained when bonded at 880 ℃ for 15？30 min.The microhardness increases with increasing the bonding temperature,while it has a peak value（HV367） when bonding time is prolonged up to 90 min.Fully equiaxed microstructures,bi-modal microstructures and fully lamellar microstructures were observed when bonded in temperature range of 780-880 ℃,at 930 ℃ or 980 ℃,respectively.The volume fraction of α phase first increases and achieves the maximum when bonded at 880 ℃ for 60 min,and then descended.
基金Project (02Gky2004) supported by Hunan Provincial Science and Technology Department, China
文摘The ultra high strength SiC particles （SiCp） reinforced Al-10%Zn-3.6%Mg-1.8%Cu-0.36%Zr-0.15% Ni composite was prepared by spray co-deposition. Microstructures of the extruded and different heat-treated bars were analyzed by transmission electron microscopy （TEM） and energy dispersive spectrometry （EDS）. Grain size of the composites prepared by two-stage solution is smaller than that by single-stage solution. After single-stage solution aging treatment, fine precipitates of both η and AlZnMgCu-rich phase can be found both intragranularly and intergranularly. While after the two-stage solution, an amorphous Si-Cu-Al-O （5 nm） layer appears at the interface. The addition of Ni and Zr modified the influence of the two-stage solution and inhibited the growth of the 7090/SiCp composite grain size. Heat treatments can significantly improve the fracture toughness of the composite. The fracture toughness first decreases then increases with the elongation of the aging time.
基金Projects(51971039,51671037)supported by the National Natural Science Foundation of ChinaProject(19KJA530001)supported by the Natural Science Research Project of Higher Education of Jiangsu,ChinaProject(KYCX21_2868)supported by the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China。
文摘Based on the diffusion channel,the influence of Si content on the microstructure evolution of iron-based hot-dip Al-χSi coating was analyzed(χ=0,1.5 wt%,3.0 wt% and 7.0 wt%).The results show that the introduction of Si makes the reaction interface change from the lingual-tooth interface of hot-dip Al to the flat interface of hot-dip Al-Si.It also reduces the thickness of the alloy layer in the coating,especially the Fe_(2)Al_(5) layer.When the Si content is 1.5 wt%or 3.0 wt%,the diffusion channel crosses the conjugate line of the two-phase region(FeAl_(3)+liquid phase)into the FeAl_(3) single-phase region,and then moves to the region with higher Si content.Next,the diffusion channel cuts off the conjugate line of FeAl_(3)phase,τ_(1)/τ_(9) phase,and Fe_(2)Al_(5)phase,which promotes the form ofτ_(1)/τ_(9) phase.The formedτ_(1)/τ_(9) phase inhibits the diffusion between Fe and Al atoms.When the Si content is 7.0 wt%,the diffusion channel passes through the two-phase region(liquid phase+τ_(5))and enters theτ_(5) single-phase region.The form ofτ_(5) single-phase region has a strong inhibitory effect on the interatomic diffusion of Fe and Al,thereby reducing the thickness of the coating,especially the Fe_(2)Al_(5)layer.
文摘Similar friction welded joints of AA-7005 aluminum rods were fabricated using different combinations of process parameters such as friction pressure(1.0, 1.5 and 2.0 MPa) and friction time(10, 15 and 20 s). Interfacial microstructure and formation of intermetallic compounds at the joint interface were evaluated via scanning electron microscopy(SEM) equipped with energy dispersive spectrum(EDS), and optical microscopy(OM). Microstructural observations reveal the formation of intermetallic phases during the welding process which cannot be extruded from the interface. Theses phases influence the tensile strength of the resultant joints. From the tensile characteristics viewpoint, the greatest tensile strength value of 365 MPa is obtained at 1.5 MPa and 15 s. Finally, the role of microstructural features on tensile strength of resultant joints is discussed.
