The effects of Cr and Cr/Mn combined additions on the semi-solid microstructure of wrought Al-Mg-Si alloys are investigated.In the Cr-added alloy,the Al-7Cr compound is formed with homogeneously distributed in theα-A...The effects of Cr and Cr/Mn combined additions on the semi-solid microstructure of wrought Al-Mg-Si alloys are investigated.In the Cr-added alloy,the Al-7Cr compound is formed with homogeneously distributed in theα-Al matrix after homogenization.Both of the Al-7Cr andα-Al-(12)Mn3-Si-2 dispersiod particles are found in the homogenized microstructure of the Cr/Mn-added alloy.In the semi-solid microstructures,the smallestα-Al grains are obtained in the 60% cold-rolled alloys.After prolonged holding time,theα-Al grain size of the Cr/Mn-added alloy is smaller than that of the Cr-added alloy.Heavy deformation by cold-rolling accelerates spheroidization of theα-Al grains.The D-SSF process is found to be useful to modify the microstructures of both the Cr-added and Cr/Mn-added Al-Mg-Si alloys.展开更多
A study was made of the fatigue fracture behaviour under different aging conditions of two Al-Mg-Si alloys with different chemical compositions and dispersoid contents.The dispersoid phase can alter the mode of the de...A study was made of the fatigue fracture behaviour under different aging conditions of two Al-Mg-Si alloys with different chemical compositions and dispersoid contents.The dispersoid phase can alter the mode of the deformation uniformity of alloys.The dispersoid it- self may decohere from the dispersoid/matrix interface under cyclic stress to form small dimples.展开更多
The solidification-precipitation behavior of Al-Mg-Si multicomponent alloys has long been an absorbing topic. Experiments were carried out to analyze the precipitation behaviors of Al-Mg-Si alloys under different heat...The solidification-precipitation behavior of Al-Mg-Si multicomponent alloys has long been an absorbing topic. Experiments were carried out to analyze the precipitation behaviors of Al-Mg-Si alloys under different heat treatments. All specimens were homogenized at 570 °C for 8 h, and then solution treated at 540 °C for 55 min. Subsequently, the specimens were age treated for different times at temperatures of 100 °C, 150 °C and 180 °C, respectively. The experimental results show that the occurrence of dispersed free zones(DFZ) is caused by the uneven distribution of dispersed phase. During the aging process, pre-β″ phases form at the initial stage and an aging temperature of 100 °C is too low to complete the transformation of pre-β″ to β″. At 150 °C, the precipitation sequence is concluded as SSSS-pre-β″-pre-β″+β″-β″-β′-β. Moreover, changes in sizes and densities of the pre-β″, β″and β′ phases during the aging process has an important influence on the evolution of microhardness and electrical resistivity. The microhardness peak value of 150 °C is similar to that of 180 °C, which is ~141 HV. While, at 100 °C, the microhardness increases slowly, and the attainable value is 127 HV up to 19 days. When the aging temperature is 100 °C, the electrical resistivity has the highest average value. When the aging temperature exceeds 100 °C, with the occurrence and growth of β″and β′, the resistivity has a distinct decrease with prolonged aging time.展开更多
This article fully discusses the basic principle of on-line quenching for aluminum alloy extrusion and process conditions to realize on-line quenching,lists on-line quenching parameters for partly common aluminum allo...This article fully discusses the basic principle of on-line quenching for aluminum alloy extrusion and process conditions to realize on-line quenching,lists on-line quenching parameters for partly common aluminum alloy extrusion,indicates chemical composition of aluminum alloy;billet quality and homogenizing treatment;pre-heating condition of billet before extrusion;quenching sensitivity of alloy and cooling speed of extrusion on-line quenching;Advanced precision water-mist-gas quenching device is a necessary and sufficient condition to realize this process.It is an advanced and effective process which can simplify process flow,improve production efficiency,shorten production period,reduce production cost and has important economic value.展开更多
The effect of solution heat treatment (SHT) on mechanical properties, microstructure and surface quality of Al-1.2Mg-0.6Si-0.2Cu-0.6Zn alloy was investigated by tensile test, Erichsen test, surface topography, scann...The effect of solution heat treatment (SHT) on mechanical properties, microstructure and surface quality of Al-1.2Mg-0.6Si-0.2Cu-0.6Zn alloy was investigated by tensile test, Erichsen test, surface topography, scanning electron microscope (SEM) and electron back-scattered diffraction (EBSD). The results indicate that with the increase in SHT temperature, yield strength and cupping test value (IE) of the sheets increase greatly and reach a peak value, then decrease. Meanwhile, intermetallic com- pounds dissolve into matrix gradually. The grains grow up as SHT temperature increases, and abnormal grain growth leads to the surface defects after solution-treated above 560 ~C. Considering mechanical properties, IE value, residual phases, grain size and surface quality of the sheets, SHT temperature for the alloy should not be higher than 550 ℃.展开更多
基于Three Dimensional Atom Probe(3DAP)以及First-Principles对Al-Si-Cu-Mg合金中团簇及后续沉淀的演变过程进行了研究。3DAP试验表明,Al-1.0Si-1.5Cu-0.5Mg合金时效0.25h后基体中主要存在点状的Si-Si团簇、Si-Mg团簇、Si-Mg-Cu团簇...基于Three Dimensional Atom Probe(3DAP)以及First-Principles对Al-Si-Cu-Mg合金中团簇及后续沉淀的演变过程进行了研究。3DAP试验表明,Al-1.0Si-1.5Cu-0.5Mg合金时效0.25h后基体中主要存在点状的Si-Si团簇、Si-Mg团簇、Si-Mg-Cu团簇,与第一性原理计算所表明的以上各结构中溶质原子间结合较强的结果相符,同时由于大量Si原子的扩散聚集,导致Si-Cu团簇结构出现;时效0.25-2h后基体中Si、Mg、Cu原子继续聚集,点状的Si-Si、Si-Cu、Si-Mg团簇长大并向针状的Si-Mg-Cu团簇演变;时效2-4h后,Si、Mg、Cu原子继续聚集,促进针状Si-Mg-Cu结构长大的同时,部分大尺寸的Si-Mg-Cu结构逐渐向板条状的Q′相转变,同时富Cu结构出现。展开更多
基金Project(2013AA032403) supported by the National High-Tech Research and Development Program of ChinaProject(YETP0409) supported by the Beijing Higher Education Young Elite Teacher Project in 2013,ChinaProject(51301016) supported by the National Natural Science Foundation of China
文摘The effects of Cr and Cr/Mn combined additions on the semi-solid microstructure of wrought Al-Mg-Si alloys are investigated.In the Cr-added alloy,the Al-7Cr compound is formed with homogeneously distributed in theα-Al matrix after homogenization.Both of the Al-7Cr andα-Al-(12)Mn3-Si-2 dispersiod particles are found in the homogenized microstructure of the Cr/Mn-added alloy.In the semi-solid microstructures,the smallestα-Al grains are obtained in the 60% cold-rolled alloys.After prolonged holding time,theα-Al grain size of the Cr/Mn-added alloy is smaller than that of the Cr-added alloy.Heavy deformation by cold-rolling accelerates spheroidization of theα-Al grains.The D-SSF process is found to be useful to modify the microstructures of both the Cr-added and Cr/Mn-added Al-Mg-Si alloys.
文摘A study was made of the fatigue fracture behaviour under different aging conditions of two Al-Mg-Si alloys with different chemical compositions and dispersoid contents.The dispersoid phase can alter the mode of the deformation uniformity of alloys.The dispersoid it- self may decohere from the dispersoid/matrix interface under cyclic stress to form small dimples.
基金financially supported by the Natural Science Foundation of Shandong Province(ZR2016EMQ11)the Major Research and Development Program of Shandong Province(2017GGX20119),China
文摘The solidification-precipitation behavior of Al-Mg-Si multicomponent alloys has long been an absorbing topic. Experiments were carried out to analyze the precipitation behaviors of Al-Mg-Si alloys under different heat treatments. All specimens were homogenized at 570 °C for 8 h, and then solution treated at 540 °C for 55 min. Subsequently, the specimens were age treated for different times at temperatures of 100 °C, 150 °C and 180 °C, respectively. The experimental results show that the occurrence of dispersed free zones(DFZ) is caused by the uneven distribution of dispersed phase. During the aging process, pre-β″ phases form at the initial stage and an aging temperature of 100 °C is too low to complete the transformation of pre-β″ to β″. At 150 °C, the precipitation sequence is concluded as SSSS-pre-β″-pre-β″+β″-β″-β′-β. Moreover, changes in sizes and densities of the pre-β″, β″and β′ phases during the aging process has an important influence on the evolution of microhardness and electrical resistivity. The microhardness peak value of 150 °C is similar to that of 180 °C, which is ~141 HV. While, at 100 °C, the microhardness increases slowly, and the attainable value is 127 HV up to 19 days. When the aging temperature is 100 °C, the electrical resistivity has the highest average value. When the aging temperature exceeds 100 °C, with the occurrence and growth of β″and β′, the resistivity has a distinct decrease with prolonged aging time.
文摘This article fully discusses the basic principle of on-line quenching for aluminum alloy extrusion and process conditions to realize on-line quenching,lists on-line quenching parameters for partly common aluminum alloy extrusion,indicates chemical composition of aluminum alloy;billet quality and homogenizing treatment;pre-heating condition of billet before extrusion;quenching sensitivity of alloy and cooling speed of extrusion on-line quenching;Advanced precision water-mist-gas quenching device is a necessary and sufficient condition to realize this process.It is an advanced and effective process which can simplify process flow,improve production efficiency,shorten production period,reduce production cost and has important economic value.
基金supported by the National Program on Key Basic Research Project of China(No. 2012CB619504)the National Natural Science Foundation of China(No.51271037)
文摘The effect of solution heat treatment (SHT) on mechanical properties, microstructure and surface quality of Al-1.2Mg-0.6Si-0.2Cu-0.6Zn alloy was investigated by tensile test, Erichsen test, surface topography, scanning electron microscope (SEM) and electron back-scattered diffraction (EBSD). The results indicate that with the increase in SHT temperature, yield strength and cupping test value (IE) of the sheets increase greatly and reach a peak value, then decrease. Meanwhile, intermetallic com- pounds dissolve into matrix gradually. The grains grow up as SHT temperature increases, and abnormal grain growth leads to the surface defects after solution-treated above 560 ~C. Considering mechanical properties, IE value, residual phases, grain size and surface quality of the sheets, SHT temperature for the alloy should not be higher than 550 ℃.
文摘基于Three Dimensional Atom Probe(3DAP)以及First-Principles对Al-Si-Cu-Mg合金中团簇及后续沉淀的演变过程进行了研究。3DAP试验表明,Al-1.0Si-1.5Cu-0.5Mg合金时效0.25h后基体中主要存在点状的Si-Si团簇、Si-Mg团簇、Si-Mg-Cu团簇,与第一性原理计算所表明的以上各结构中溶质原子间结合较强的结果相符,同时由于大量Si原子的扩散聚集,导致Si-Cu团簇结构出现;时效0.25-2h后基体中Si、Mg、Cu原子继续聚集,点状的Si-Si、Si-Cu、Si-Mg团簇长大并向针状的Si-Mg-Cu团簇演变;时效2-4h后,Si、Mg、Cu原子继续聚集,促进针状Si-Mg-Cu结构长大的同时,部分大尺寸的Si-Mg-Cu结构逐渐向板条状的Q′相转变,同时富Cu结构出现。