The effect of Sr on modification and refinement of the Mg 2 Si phase in an AZ61-0.7Si magnesium alloy has been investigated and analyzed.The results indicate that Sr can effectively modify and refine the Chinese-scrip...The effect of Sr on modification and refinement of the Mg 2 Si phase in an AZ61-0.7Si magnesium alloy has been investigated and analyzed.The results indicate that Sr can effectively modify and refine the Chinese-script shaped Mg2Si phase in the AZ61-0.7Si alloy.By adding 0.06wt.%-0.12wt.%Sr to AZ61-0.7Si alloy,the Mg2Si phase in the alloy can be changed from the initial coarse Chinese-script shape to fine granule and/or irregular polygonal shapes.Accordingly,the Sr-containing AZ61-0.7Si alloy exhibits higher tensile and creep properties than the AZ61-0.7Si alloy without Sr modification.The mechanism on modification and refinement of the Mg2Si phase in Sr-containing AZ61-0.7Si alloy is possibly related to the following two aspects:(1)adding Sr may form the Al4Sr phase which can serve as the heterogeneous nucleus for the Mg2Si particles and/or(2)adding Sr may lower the onset crystallizing temperature and increase the undercooling level.展开更多
The effects of Sb and Sr on the modification and refinement of Mg17Al12 and Mg2Si phases in Mg- 12Al-0.7Si alloy were investigated and compared. The microstructure and mechanical properties of Mg-12Al0.7Si alloy and i...The effects of Sb and Sr on the modification and refinement of Mg17Al12 and Mg2Si phases in Mg- 12Al-0.7Si alloy were investigated and compared. The microstructure and mechanical properties of Mg-12Al0.7Si alloy and its modification mechanism by Sb and Sr were investigated using a scanning electron microscope （SEM）, an energy dispersive spectrometer （EDS）, X-ray diffraction （XRD） and differential thermal analysis （DTA）. The results indicate that by adding 0.5wt.% Sb to the Mg-12Al-0.7Si alloy, the Mg17Al12 phase was refined and broken into some discontinuous island structures. However, some network Mg17Al12 phases still can be detected in Mg-12Al-0.7Si-0.09Sr alloy. Therefore, Sb performs better in modification and refinement of Mg17Al12 phase than does Sr. Small amounts of fine polygonal shaped Mg2Si phases were found in Mg-12AI-0.7Si-0.5Sb alloy, while the morphology of Mg2Si phases in Mg-12Al-0.7Si-0.09Sr alloy changed from the coarse Chinese script shapes to fine granule and irregular polygonal shapes, indicating that the effects of modification and refinement on Mg2Si phase are more significant by adding 0.09wt.% Sr than 0.5wt.% Sb. The ultimate tensile strengths of the Sb and Sr modified Mg-12Al-0.7Si alloys were considerably increased both at room temperature and at 200 ℃.展开更多
A Mg-8%Al-1%Si alloy with semisolid microstructure was fabricated by isothermal heat treatment process. The effects of isothermal process parameters such as holding temperature and holding time on the microstructure o...A Mg-8%Al-1%Si alloy with semisolid microstructure was fabricated by isothermal heat treatment process. The effects of isothermal process parameters such as holding temperature and holding time on the microstructure of Mg-8%Al-1%Si alloy were investigated. The results show that a non-dendritic microstructure could be obtained by isothermal heat treatment. With increasing holding temperature from 560 to 575 °C or holding time from 5 to 30 min, the liquid volume fraction increases, the average size of α-Mg grains grows larger and globular tendency becomes more obvious. In addition, the Mg2Si phase transforms from Chinese script shape to granule shape. The morphology modification mechanisium of Mg2Si phase in Mg-8%Al-1%Si alloy during the semisolid isothermal heat treatment was also studied.展开更多
The microstructures and mechanical properties of as-cast Mg-5 Sn-1 Si magnesium alloy modified with trace elements Y,Bi,Sb and Sr were investigated and compared.Results show that the microstructure of the as-cast Mg-5...The microstructures and mechanical properties of as-cast Mg-5 Sn-1 Si magnesium alloy modified with trace elements Y,Bi,Sb and Sr were investigated and compared.Results show that the microstructure of the as-cast Mg-5 Sn-1 Si alloy consists ofα-Mg,Mg_(2) Si,Mg_(2) Sn and Mg_(2)(Si_xSn_(1-x))phases.After adding 0.8 wt.%Y,0.3 wt.%Bi,0.9 wt.%Sb and 0.9 wt.%Sr,respectively into the Mg-5 Sn-1 Si magnesium alloy,Mg_(24)Y_(5),Mg_(3) Bi_(2),Mg_(3) Sb_(2) and Mg_(2) Sr phases are precipitated accordingly.Trace elements can refineα-Mg grain and Chinese scriptshaped Mg_(2) Si phase.Refinement efficiency of different trace elements onα-Mg grain and Mg_(2) Si phase is varied.Sr element has the best refinement effect,followed by Sb and Bi,while Y has the least refinement effect.Mg-5 Sn-1 Si-0.9 Sr alloy has higher tensile properties than the other three modified alloys.The refinement mechanism of Y,Bi and Sr elements on Mg-5 Sn-1 Si magnesium alloy can be explained by the growth restriction factors and the solute undercooling.For Mg-5 Sn-1 Si-0.9 Sb alloy,the heterogeneous nuclei of Mg_(3) Sb_(2) phase is the main reason for the refinement of grains and second phases.展开更多
The effects of solution heat treatment on the microstructure and mechanical properties of AZ61-0.7Si magnesium alloy were investigated.The results indicate that the solution heat treatment can modify the Chinese scrip...The effects of solution heat treatment on the microstructure and mechanical properties of AZ61-0.7Si magnesium alloy were investigated.The results indicate that the solution heat treatment can modify the Chinese script shaped Mg2Si phases in the AZ61-0.7Si magnesium alloy.After being solutionized at 420℃ for 16-48 h,the morphology of the Mg2Si phases in the AZ61-0.7Si alloy changes from the Chinese script shape to the short pole and block shapes.Accordingly,the tensile and creep properties of the AZ61-0.7Si alloy are improved.After being solutionized at 420℃ for 24 h and followed by aging treatment at 200℃ for 12 h,the heat-treated alloy exhibits relatively high tensile and creep properties than those of the as-cast alloy.展开更多
The modification and refinement of Mg2Si phase is thought to be one of the key aspects to improve the mechanical properties of Si-containing magnesium alloys. In this article, the effects of Sr on the microstructure, ...The modification and refinement of Mg2Si phase is thought to be one of the key aspects to improve the mechanical properties of Si-containing magnesium alloys. In this article, the effects of Sr on the microstructure, tensile and creep properties of AZ61-0.7Si magnesium alloy were investigated. The results indicate that adding small amounts of Sr to AZ61-0.7Si alloy can modify and refine Chinese script shaped Mg2Si phases in the alloy. After adding 0.03wt%-0.09wt% Sr to AZ61-0.7Si alloy, the Mg2Si phases in the alloy change from the coarse Chinese script shape to fine granule and/or irregular polygonal shapes. The modification and refinement mechanisms of Mg2Si phases in Sr-containing AZ61-0.7Si alloys are possibly related to the reduction of growth rate and the enhancement of nucleation ratio for Mg2Si particles during the solidification process. Owing to the modification and refinement of Mg2Si phases, the tensile and creep properties of Sr-containing AZ61-0.7Si alloys are greatly improved.展开更多
The effects of isothermal holding time on the semisolid microstructure of Mg-9Al-1Si(mass fraction,%)alloy were investigated.The research results indicate that the Mg-9Al-1Si alloy with non-dendritic microstructure ca...The effects of isothermal holding time on the semisolid microstructure of Mg-9Al-1Si(mass fraction,%)alloy were investigated.The research results indicate that the Mg-9Al-1Si alloy with non-dendritic microstructure can be produced by the semi-solid isothermal heat treatment.With holding time varying from 5 to 30 min,the volume fraction of liquid is gradually enlarged from 29.3%to 38.6%,the morphology ofα-Mg grains changes from initial dendritic shape to spherical types and their average sizes increases from 41.1 to 56.1μm.In addition,during the isothermal heat treatment,the eutectic Mg2Si phase changes from the initial Chinese script shape to granule and/or polygon shape in Mg-9Al-1Si alloy.The modification of Mg2Si phase is possibly attributed to a shift of the eutectic composition of the liquid in semi-solid slurries,towards lower silicon contents with increasing Al content due to a redistribution of Al during isothermal heat treatment.展开更多
A new Mg−10%Al−1%Zn−1%Si alloy with non-dendritic microstructure was prepared by strain induced melt activation(SIMA)process.The effect of compression ratio on the evolution of semisolid microstructure of the experime...A new Mg−10%Al−1%Zn−1%Si alloy with non-dendritic microstructure was prepared by strain induced melt activation(SIMA)process.The effect of compression ratio on the evolution of semisolid microstructure of the experimental alloy was investigated.The results indicate that the average size ofα-Mg grains decreases and spheroidizing tendency becomes more obvious with the compression ratios increasing from 0 to 40%.In addition,the eutectic Mg2Si phase in the Mg−10%Al−1%Zn−1%Si alloy transforms completely from the initial fishbone shape to globular shape by SIMA process.With the increasing of compression ratio,the morphology and average size of Mg2Si phases do not change obviously.The morphology modification mechanism of Mg2Si phase in Mg−10%Al−1%Zn−1%Si alloy by SIMA process was also studied.展开更多
Magnesium alloy has been considered as one of the third-generation biomaterials for the regeneration and support of functional bone tissue.As a regeneration implant material with great potential applications,in-situ M...Magnesium alloy has been considered as one of the third-generation biomaterials for the regeneration and support of functional bone tissue.As a regeneration implant material with great potential applications,in-situ Mg_(2)Si phase reinforced Mg-6Zn cast alloy was comprehensively studied and expected to possess excellent mechanical properties via the refining and modifying of Mg_(2)Si reinforcements.The present study demonstrates that the primary and eutectic Mg_(2)Si phase can be greatly modified by the yttrium(Y)addition.The size of the primary Mg_(2)Si phases can be reduced to~20μm with an addition of 0.5 wt.%Y.This phenomenon is mainly attributed to the poisoning effect of the Y element.Moreover,wear resistance and tensile properties of the ternary alloy have also been improved by the Y addition.Mg-6Zn-4Si-0.5Y alloy exhibits optimal tensile properties and wears resistance.The ultimate tensile strength and the elongation of the alloy with 0.5 wt.%Y are 50%and 65%higher than those of the ternary alloy,respectively.Excessive Y addition(1.0 wt.%)deteriorates the tensile properties of Mg-Zn-Si alloy.The improvement of the tensile properties is mainly due to the modification of primary and eutectic Mg_(2)Si phases as well as the solid solution strengthening of the Y atoms.This study provides a certain implication for the application of Mg-Zn-Si alloys containing Y elements as regeneration implants.展开更多
基金supported by the National Natural Science Funds for Distinguished Young Scholar in China(No.50725413)the Major State Basic Research Development Program of China(973)(No.2007CB613704)+1 种基金the Natural Science Foundation Project of CQ CSTC(No.2007BB4400)Chongqing Science and Technology Commission in China(No.2006AA4012-9-6).
文摘The effect of Sr on modification and refinement of the Mg 2 Si phase in an AZ61-0.7Si magnesium alloy has been investigated and analyzed.The results indicate that Sr can effectively modify and refine the Chinese-script shaped Mg2Si phase in the AZ61-0.7Si alloy.By adding 0.06wt.%-0.12wt.%Sr to AZ61-0.7Si alloy,the Mg2Si phase in the alloy can be changed from the initial coarse Chinese-script shape to fine granule and/or irregular polygonal shapes.Accordingly,the Sr-containing AZ61-0.7Si alloy exhibits higher tensile and creep properties than the AZ61-0.7Si alloy without Sr modification.The mechanism on modification and refinement of the Mg2Si phase in Sr-containing AZ61-0.7Si alloy is possibly related to the following two aspects:(1)adding Sr may form the Al4Sr phase which can serve as the heterogeneous nucleus for the Mg2Si particles and/or(2)adding Sr may lower the onset crystallizing temperature and increase the undercooling level.
基金financially supported by the National Natural Science Foundation of China(Grant nos.:51301118,51404166)the Projects of International Cooperation in Shanxi province,China(Grant no.:2014081002)and the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi province,China(Grant nos.:2013108,2014120)
文摘The effects of Sb and Sr on the modification and refinement of Mg17Al12 and Mg2Si phases in Mg- 12Al-0.7Si alloy were investigated and compared. The microstructure and mechanical properties of Mg-12Al0.7Si alloy and its modification mechanism by Sb and Sr were investigated using a scanning electron microscope （SEM）, an energy dispersive spectrometer （EDS）, X-ray diffraction （XRD） and differential thermal analysis （DTA）. The results indicate that by adding 0.5wt.% Sb to the Mg-12Al-0.7Si alloy, the Mg17Al12 phase was refined and broken into some discontinuous island structures. However, some network Mg17Al12 phases still can be detected in Mg-12Al-0.7Si-0.09Sr alloy. Therefore, Sb performs better in modification and refinement of Mg17Al12 phase than does Sr. Small amounts of fine polygonal shaped Mg2Si phases were found in Mg-12AI-0.7Si-0.5Sb alloy, while the morphology of Mg2Si phases in Mg-12Al-0.7Si-0.09Sr alloy changed from the coarse Chinese script shapes to fine granule and irregular polygonal shapes, indicating that the effects of modification and refinement on Mg2Si phase are more significant by adding 0.09wt.% Sr than 0.5wt.% Sb. The ultimate tensile strengths of the Sb and Sr modified Mg-12Al-0.7Si alloys were considerably increased both at room temperature and at 200 ℃.
基金Project(2009AA03Z423)supported by the High-tech Research and Development Program of ChinaProject(51071055)supported by the National Natural Science Foundation of ChinaProject(HEUFT05038)supported by the Basic Research Foundation of Harbin Engineering University,China
文摘A Mg-8%Al-1%Si alloy with semisolid microstructure was fabricated by isothermal heat treatment process. The effects of isothermal process parameters such as holding temperature and holding time on the microstructure of Mg-8%Al-1%Si alloy were investigated. The results show that a non-dendritic microstructure could be obtained by isothermal heat treatment. With increasing holding temperature from 560 to 575 °C or holding time from 5 to 30 min, the liquid volume fraction increases, the average size of α-Mg grains grows larger and globular tendency becomes more obvious. In addition, the Mg2Si phase transforms from Chinese script shape to granule shape. The morphology modification mechanisium of Mg2Si phase in Mg-8%Al-1%Si alloy during the semisolid isothermal heat treatment was also studied.
基金the financial support by the Natioal Natural Science Foundation of China(Nos.:51571086 and 51271073)the financial support from the Natural Science Foundation of Henan Polytechnic University(No.:B2010-20)。
文摘The microstructures and mechanical properties of as-cast Mg-5 Sn-1 Si magnesium alloy modified with trace elements Y,Bi,Sb and Sr were investigated and compared.Results show that the microstructure of the as-cast Mg-5 Sn-1 Si alloy consists ofα-Mg,Mg_(2) Si,Mg_(2) Sn and Mg_(2)(Si_xSn_(1-x))phases.After adding 0.8 wt.%Y,0.3 wt.%Bi,0.9 wt.%Sb and 0.9 wt.%Sr,respectively into the Mg-5 Sn-1 Si magnesium alloy,Mg_(24)Y_(5),Mg_(3) Bi_(2),Mg_(3) Sb_(2) and Mg_(2) Sr phases are precipitated accordingly.Trace elements can refineα-Mg grain and Chinese scriptshaped Mg_(2) Si phase.Refinement efficiency of different trace elements onα-Mg grain and Mg_(2) Si phase is varied.Sr element has the best refinement effect,followed by Sb and Bi,while Y has the least refinement effect.Mg-5 Sn-1 Si-0.9 Sr alloy has higher tensile properties than the other three modified alloys.The refinement mechanism of Y,Bi and Sr elements on Mg-5 Sn-1 Si magnesium alloy can be explained by the growth restriction factors and the solute undercooling.For Mg-5 Sn-1 Si-0.9 Sb alloy,the heterogeneous nuclei of Mg_(3) Sb_(2) phase is the main reason for the refinement of grains and second phases.
基金Project(50725413)supported by the National Natural Science Foundation of ChinaProject(2007CB613704)supported by the National Basic Research Program of ChinaProject(2006AA4012-9-6,2007BB4400)supported by the Chongqing Science and Technology Commission,China
文摘The effects of solution heat treatment on the microstructure and mechanical properties of AZ61-0.7Si magnesium alloy were investigated.The results indicate that the solution heat treatment can modify the Chinese script shaped Mg2Si phases in the AZ61-0.7Si magnesium alloy.After being solutionized at 420℃ for 16-48 h,the morphology of the Mg2Si phases in the AZ61-0.7Si alloy changes from the Chinese script shape to the short pole and block shapes.Accordingly,the tensile and creep properties of the AZ61-0.7Si alloy are improved.After being solutionized at 420℃ for 24 h and followed by aging treatment at 200℃ for 12 h,the heat-treated alloy exhibits relatively high tensile and creep properties than those of the as-cast alloy.
基金supported by the National Science Fund for Distinguished Young Scholars (No.50725413)the Major State Basic Research and Development Program of China (No.2007CB613704)+1 种基金the Natural Science Foundation Project of CQ CSTC (No.2007BB4400)Chongqing Science and Technology Commission in China (No.2006AA4012-9-6)
文摘The modification and refinement of Mg2Si phase is thought to be one of the key aspects to improve the mechanical properties of Si-containing magnesium alloys. In this article, the effects of Sr on the microstructure, tensile and creep properties of AZ61-0.7Si magnesium alloy were investigated. The results indicate that adding small amounts of Sr to AZ61-0.7Si alloy can modify and refine Chinese script shaped Mg2Si phases in the alloy. After adding 0.03wt%-0.09wt% Sr to AZ61-0.7Si alloy, the Mg2Si phases in the alloy change from the coarse Chinese script shape to fine granule and/or irregular polygonal shapes. The modification and refinement mechanisms of Mg2Si phases in Sr-containing AZ61-0.7Si alloys are possibly related to the reduction of growth rate and the enhancement of nucleation ratio for Mg2Si particles during the solidification process. Owing to the modification and refinement of Mg2Si phases, the tensile and creep properties of Sr-containing AZ61-0.7Si alloys are greatly improved.
基金Project(HEUFT05038)supported by the Basic Research Foundation of Harbin Engineering University,ChinaProject(2009AA03Z423)supported by the National High-Tech Research and Development Program of China
文摘The effects of isothermal holding time on the semisolid microstructure of Mg-9Al-1Si(mass fraction,%)alloy were investigated.The research results indicate that the Mg-9Al-1Si alloy with non-dendritic microstructure can be produced by the semi-solid isothermal heat treatment.With holding time varying from 5 to 30 min,the volume fraction of liquid is gradually enlarged from 29.3%to 38.6%,the morphology ofα-Mg grains changes from initial dendritic shape to spherical types and their average sizes increases from 41.1 to 56.1μm.In addition,during the isothermal heat treatment,the eutectic Mg2Si phase changes from the initial Chinese script shape to granule and/or polygon shape in Mg-9Al-1Si alloy.The modification of Mg2Si phase is possibly attributed to a shift of the eutectic composition of the liquid in semi-solid slurries,towards lower silicon contents with increasing Al content due to a redistribution of Al during isothermal heat treatment.
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(Nos.41807235,50674038).
文摘A new Mg−10%Al−1%Zn−1%Si alloy with non-dendritic microstructure was prepared by strain induced melt activation(SIMA)process.The effect of compression ratio on the evolution of semisolid microstructure of the experimental alloy was investigated.The results indicate that the average size ofα-Mg grains decreases and spheroidizing tendency becomes more obvious with the compression ratios increasing from 0 to 40%.In addition,the eutectic Mg2Si phase in the Mg−10%Al−1%Zn−1%Si alloy transforms completely from the initial fishbone shape to globular shape by SIMA process.With the increasing of compression ratio,the morphology and average size of Mg2Si phases do not change obviously.The morphology modification mechanism of Mg2Si phase in Mg−10%Al−1%Zn−1%Si alloy by SIMA process was also studied.
基金supported by Natural Science Foundation of the Jiangsu Higher Education Institutions of China(19KJD430004)the Fund of the Jiangsu CHINA-ISRAEL Industrial Technology Research Institute and Changzhou Sci&Tech Program(Nos.CJ20190042,CJ20200046).
文摘Magnesium alloy has been considered as one of the third-generation biomaterials for the regeneration and support of functional bone tissue.As a regeneration implant material with great potential applications,in-situ Mg_(2)Si phase reinforced Mg-6Zn cast alloy was comprehensively studied and expected to possess excellent mechanical properties via the refining and modifying of Mg_(2)Si reinforcements.The present study demonstrates that the primary and eutectic Mg_(2)Si phase can be greatly modified by the yttrium(Y)addition.The size of the primary Mg_(2)Si phases can be reduced to~20μm with an addition of 0.5 wt.%Y.This phenomenon is mainly attributed to the poisoning effect of the Y element.Moreover,wear resistance and tensile properties of the ternary alloy have also been improved by the Y addition.Mg-6Zn-4Si-0.5Y alloy exhibits optimal tensile properties and wears resistance.The ultimate tensile strength and the elongation of the alloy with 0.5 wt.%Y are 50%and 65%higher than those of the ternary alloy,respectively.Excessive Y addition(1.0 wt.%)deteriorates the tensile properties of Mg-Zn-Si alloy.The improvement of the tensile properties is mainly due to the modification of primary and eutectic Mg_(2)Si phases as well as the solid solution strengthening of the Y atoms.This study provides a certain implication for the application of Mg-Zn-Si alloys containing Y elements as regeneration implants.
