The effectiveness of Ca or Gd addition on ductility and formability of Mg-Zn-Zr based dilute alloys in deep drawing has not been systematically compared previously.In this study,formable Mg-Zn-Gd-Zr and Mg-Zn-Ca-Zr sh...The effectiveness of Ca or Gd addition on ductility and formability of Mg-Zn-Zr based dilute alloys in deep drawing has not been systematically compared previously.In this study,formable Mg-Zn-Gd-Zr and Mg-Zn-Ca-Zr sheet alloys are produced by hot rolling.These sheets have similarly weakened basal texture,but the sheet of the Mg-Zn-Gd-Zr alloys has higher ductility and formability than that of Mg-Zn-Ca-Zr alloys.The combined addition of 0.2wt%Ca and 0.4wt%Gd to the Mg-1Zn-0.5Zr(wt%)alloy leads to a Mg-1Zn-0.4Gd-0.2Ca-0.5Zr alloy that has even better ductility,and its formability during deep drawing is comparable to the benchmark Al6016 sheet.An increase in Ca content from 0.2wt%to 0.5wt%leads to decreased sheet ductility and formability,predominantly due to grain boundary embrittlement.展开更多
In this paper, repeated unidirectional bending (RUB), was applied to improve the texture of AZ31B magnesium alloy sheets so as to enhance their stamping properties. The samples undergoing RUB were annealed at differ...In this paper, repeated unidirectional bending (RUB), was applied to improve the texture of AZ31B magnesium alloy sheets so as to enhance their stamping properties. The samples undergoing RUB were annealed at different temperatures. The mechanical properties, formability, textural components and microstructure of the samples before and after RUB were characterized and compared. It was found that the basal textural component was reduced dramatically by RUB, and that (1212) and (1211) textural components appeared. Annealing has a great effect on the mechanical properties of samples undergoing RUB. The plasticity and stamping formability of samples were greatly improved by RUB and annealing at 260℃ for 1 h, and elongation to fracture and Erichsen value were increased to 38% and 67%, respectively.展开更多
The formabilityof AZ31 sheet begins to increase drastically at 150℃.The incremental forming technique was thus applied to AZ31 sheet at 150℃to utilize the formability to its fullest capacity at the lowest possible t...The formabilityof AZ31 sheet begins to increase drastically at 150℃.The incremental forming technique was thus applied to AZ31 sheet at 150℃to utilize the formability to its fullest capacity at the lowest possible temperature for forming applications.A surface scanning technique was used followed by the tool path generation to incrementally form an egg surface.After thorough examination of various tool paths,the surface was most successfully produced by forming an intermediate shape followed by a series of tool paths.Flexible scale stickers were devised to improve the accuracy in the measurement of grid deformation.展开更多
Repeatedly unidirectional bending(RUB) was applied to the magnesium alloy sheet to improve the basal texture.The effect of RUB temperature on resulting structure and room temperature properties was investigated.The te...Repeatedly unidirectional bending(RUB) was applied to the magnesium alloy sheet to improve the basal texture.The effect of RUB temperature on resulting structure and room temperature properties was investigated.The texture components of the sheet undergoing RUB at recovery temperature were similar to those of the sheet undergoing RUB at room temperature(RT).As the RUB temperature increased to above recrystallization temperature,the texture components became more disperse and the pyramidal components increased.With the increase of RUB temperature,the grain size near the surface of the sheets undergoing RUB tended to grow up.When the sheets were processed by RUB at medium-high temperature followed by annealing at 533 K,the yield strength and fracture elongation were lower than those of the cold rolled sheet;however,the Erichsen value was slightly higher than that of the cold rolled sheet.The sheet undergoing RUB at RT followed by annealing at 533 K represented the best mechanical properties.展开更多
Equal channel angular pressing (ECAP) processing and annealing were applied to the AZ31 magnesium alloy sheets to evaluate the potential improvement in the mechanical properties and formability. The ECAP experiment ...Equal channel angular pressing (ECAP) processing and annealing were applied to the AZ31 magnesium alloy sheets to evaluate the potential improvement in the mechanical properties and formability. The ECAP experiment was conducted at 300 ℃ in a die having an included angle of 90o between two channels by the BCZ route with the sheets rotated by 90°about the normal axis of plate plane. The tensile tests and conical cup tests were conducted at various temperatures from 20 to 250 ℃. The experimental results indicated that improving the working temperatures could lead to the soft in the material and the enhancement of ductility. Comparatively, the ECAPed AZ31 alloy sheets showed the lower yield strength and smaller conical cup value (CCV) than the unECAPed counterpart in the room temperature. The difference in yield strength between them became small in the elevated temperature, but the ECAPed samples still had the smaller CCV value, implying the improved formability. The texture of the AZ31 alloy sheets could be modified by ECAP and the decrease in the yield strength and more uniform deformation realized in the material, so the formability of AZ31 alloy sheets was improved.展开更多
The evolution of texture during the annealing and hot rolling process of extruded AZ31 magnesium alloy sheets was studied. There are two kinds of texture components in the extruded AZ31 sheets. One is {0002}<1010&g...The evolution of texture during the annealing and hot rolling process of extruded AZ31 magnesium alloy sheets was studied. There are two kinds of texture components in the extruded AZ31 sheets. One is {0002}<1010> and the other is {1010}<1120>. The {0002}<1010>component predominates. After annealing at 723 K for 3 h, both {0002}<1010> and {1010}<1120> components are strengthened moderately. This indicates that grains with both two components mentioned above grow faster than those with other orientations. The {1010}<1120> component disappears and the intensity of {0002}<1010> component decreases significantly after hot rolling with a 30% reduction at 623 K. This is mainly attributed to rotational dynamic recrystallization (RDX) during the hot rolling.展开更多
Microstructures, tensile properties, fracture characteristics of commercial AZ31 magnesium alloy thin sheet were studied by optical microscopy, scanning electron microscopy and uniaxial tensile test. Tensile tests wer...Microstructures, tensile properties, fracture characteristics of commercial AZ31 magnesium alloy thin sheet were studied by optical microscopy, scanning electron microscopy and uniaxial tensile test. Tensile tests were carried out at room temperature and 473K, with strain rates of 8.3×10 -44.2×10 -3s -1. The results show that grain refinement effects are better at high temperature, and it increases with the decrease of strain rate at 473K. Compared with that tested at room temperature, no apparent uniform plastic deformation stage exists in the stress—strain curves tested at 473K; afterwards, the stress—strain curve presents wavelike downward under condition of the small strain rate. Yield strength and tensile strength of the alloy decrease drastically while the elongation increases greatly. With the increase of strain rate, yield strength and tensile strength of the alloy increase, but the elongation decreases. The fracture of the alloy tested at room temperature is quasi-cleavage failure and ductile failure at 473K.展开更多
Electric product house of magnesium alloy sheet is usually obtained by warm stamping owing to its poor plasticity and formability at room temperature.The formability of AZ31B magnesium alloy sheet can be improved by r...Electric product house of magnesium alloy sheet is usually obtained by warm stamping owing to its poor plasticity and formability at room temperature.The formability of AZ31B magnesium alloy sheet can be improved by repeated unidirectional bending(RUB)process through control of(0002)basal texture.Compared with as-received sheet,the Erichsen value(IE)of the sheet underwent RUB process increases to 5.90 from 3.53 at room temperature.It is also confirmed that cell phone houses could be stamped successfully in crank press with AZ31B magnesium alloy sheets underwent RUB process.It provides an alternative to the electronics industry in the application of magnesium alloys.展开更多
A high-ductility ZME200(Mg–2.3Zn–0.4Mn–0.2Ce^(1))alloy was newly developed for vehicle closure and structure applications,based on an earlier ZE20(Mg–2.0Zn–0.2Ce)alloy for extrusion applications.Previous study in...A high-ductility ZME200(Mg–2.3Zn–0.4Mn–0.2Ce^(1))alloy was newly developed for vehicle closure and structure applications,based on an earlier ZE20(Mg–2.0Zn–0.2Ce)alloy for extrusion applications.Previous study indicates that the hot deformation behavior of as-cast ZME200 alloy varies with processing parameters,namely temperature and strain rate.In this follow-up study,a conventional rolling process was optimized to obtain magnesium sheets with a very fine grain structure and high ductility.The microstructure,mechanical properties,and corrosion resistances of ZME200 alloy were investigated,and compared with those of commercial AZ31 magnesium alloy.It was demonstrated that the ZME200 alloy sheet exhibits extraordinarily higher ductility(36%in tensile elongation),much superior stretch formability(an Erichsen value of 9.5),lower anisotropy,comparable strength and corrosion resistance to AZ31 alloy.The unique RD–TD double split texture with remarkably reduced intensity and grain refinement gives rise to the significantly improved ductility and formability at room-temperature.展开更多
Twin roll casting was commercialized for a strip production from ferrous and non-ferrous alloys in the 1950 s;however,its application to magnesium has proven difficult and still creates major challenges.This report de...Twin roll casting was commercialized for a strip production from ferrous and non-ferrous alloys in the 1950 s;however,its application to magnesium has proven difficult and still creates major challenges.This report describes global efforts in expanding manufacturing capabilities of magnesium sheet through twin roll casting path,offering many benefits,including a reduction in number of processing steps and energy savings.In addition to hardware design,alloy transformation during processing,product microstructure and properties,examples of successful solutions along with present technology and knowledge limitations are discussed.A particular attention is paid to developments at Canmet MATERIALS,having the only in North America pilot scale twin roll casting facility,devoted to magnesium.Efforts are described that aim at design of new magnesium alloys,which could take advantage of unique processing conditions during twin roll casting and contribute to the overall progress in magnesium sheet manufacturing.展开更多
The deformation behavior of the Mg-Al-Mn sheet was investigated during tensile loading along the rolling(RD)and transversal direction(TD)with special attention to the early stage of deformation.The activity of disloca...The deformation behavior of the Mg-Al-Mn sheet was investigated during tensile loading along the rolling(RD)and transversal direction(TD)with special attention to the early stage of deformation.The activity of dislocation slip systems during the transition from elastic to plastic deformation was revealed by the acoustic emission(AE)technique.The parametrization and statistical AE analysis using the adaptive sequential k-mean(ASK)clustering provided necessary information about the individual deformation mechanisms and their evolution.The AE findings were supported by microstructural analyses,including in-situ secondary electron(SE)imaging and Schmid factor estimation for the activity of particular dislocation slip systems with respect to the loading direction.It was found that basal slip is the dominating mechanism up to the stress of~80 MPa in both loading directions with an absolute dominance during the RD-loading,while during the TD-loading,the contribution of prismatic slip to the deformation at stresses above 50 MPa was determined.Below the yielding in both loading directions,the predominance of prismatic over pyramidal slip was found at the stress in the range of 80-110 MPa and the opposite tendency occurred at stresses between 110 and 140 MPa.展开更多
The microstructures and mechanical properties of hot rolled AZ31 Mg alloy sheets were studied to understand the microstrucrure evolution during AZ31 Mg alloy hot rolling process. The roller was heated to 180℃with bur...The microstructures and mechanical properties of hot rolled AZ31 Mg alloy sheets were studied to understand the microstrucrure evolution during AZ31 Mg alloy hot rolling process. The roller was heated to 180℃with burning hydrogen, and the extruded plates were rolled at 400℃from 10 to 1 mm with a reduction of 30% in thickness per pass. The result shows that there is no side-cracking of these rolled sheets every pass. The extruded microstructures are greatly refined and mechanical properties are improved. The fine grains of about 4μm were obtained of the final 0.9 mm sheets.展开更多
A comprehensive consideration based on castability or plastic formability, as well as mechanical properties for development of either cast magnesium alloys or wrought magnesium alloys is a very important issue. To dev...A comprehensive consideration based on castability or plastic formability, as well as mechanical properties for development of either cast magnesium alloys or wrought magnesium alloys is a very important issue. To develop new magnesium alloy sheets with high formability at room temperature, the microstructure, texture, ductility and anisotropy of rolled Mg-Zn-Gd alloy sheets were investigated. The sheets exhibit an excellent ultimate elongation of nearly 50% and an uniform elongation greater than 30% with a very low planar anisotropy. The new sheet has a random basal texture and the basal pole is tilted by maximum 40° from the normal direction towards the transverse direction. The majority of grains in the tilted texture have an orientation favorable for both basal slip and tensile twining because of their high Schmid factor. The low planar anisotropy, the large uniform elongations and the high strain hardening rate observed in the Mg-Zn-Gd sheets result in excellent room temperature formability, the Erichsen values reach ~8, well comparable with the conventional aluminum alloys sheets at room temperature. The solidification pathways and phase equilibria of Mg-Al-Ca alloys have been profoundly investigated by using thermal analysis and thermodynamic calculations. The relationship between hot tearing tendency and alloy compositions were discussed in terms of strength of the mushy zone, solidification pathways and feeding mechanisms, et al. Thixoforming refers to as that metal components are formed in their semi-solid state. Criteria for thixoforming are summarized and then the thixoformability of Mg-Al-Ca based alloys (AC alloys) are evaluated using the thermodynamic calculations based on the consideration of metallurgical parameters.展开更多
Zn-Mg alloy coatings were obtained by physical vapor deposition (PVD) on electroplated steel sheets. Study on the formation of intermetallic phases in the coatings was conducted through the use of X-ray diffraction ...Zn-Mg alloy coatings were obtained by physical vapor deposition (PVD) on electroplated steel sheets. Study on the formation of intermetallic phases in the coatings was conducted through the use of X-ray diffraction (XRD) ,scanning electron microscope (SEM) and glow discharge optical emission spectrometry (GDOES). It is found that MgZn2 is the main Zn-Mg alloy phase formed after heat treatment. The formation of Mg-Zn intermetallic phases is controlled not only by thermodynamics, but also by kinetics. MgZn2 has different morphologies, such as laminar structure,porous structure and floc-like structure,which are mainly determined by the annealing temperature. Obvious diffusion of Mg starts at 350 ℃, and the diffusion of iron increases significantly when the temperature is elevated to 380℃.展开更多
基金support from the Australian Research Council and Baosteel Company。
文摘The effectiveness of Ca or Gd addition on ductility and formability of Mg-Zn-Zr based dilute alloys in deep drawing has not been systematically compared previously.In this study,formable Mg-Zn-Gd-Zr and Mg-Zn-Ca-Zr sheet alloys are produced by hot rolling.These sheets have similarly weakened basal texture,but the sheet of the Mg-Zn-Gd-Zr alloys has higher ductility and formability than that of Mg-Zn-Ca-Zr alloys.The combined addition of 0.2wt%Ca and 0.4wt%Gd to the Mg-1Zn-0.5Zr(wt%)alloy leads to a Mg-1Zn-0.4Gd-0.2Ca-0.5Zr alloy that has even better ductility,and its formability during deep drawing is comparable to the benchmark Al6016 sheet.An increase in Ca content from 0.2wt%to 0.5wt%leads to decreased sheet ductility and formability,predominantly due to grain boundary embrittlement.
基金supported by the National Natural Science Foundation of China under Grant No. 50504019Natural Science Foundation Project of CQ CSTC under Grant No. 2008BB4040
文摘In this paper, repeated unidirectional bending (RUB), was applied to improve the texture of AZ31B magnesium alloy sheets so as to enhance their stamping properties. The samples undergoing RUB were annealed at different temperatures. The mechanical properties, formability, textural components and microstructure of the samples before and after RUB were characterized and compared. It was found that the basal textural component was reduced dramatically by RUB, and that (1212) and (1211) textural components appeared. Annealing has a great effect on the mechanical properties of samples undergoing RUB. The plasticity and stamping formability of samples were greatly improved by RUB and annealing at 260℃ for 1 h, and elongation to fracture and Erichsen value were increased to 38% and 67%, respectively.
基金Project(R01-2006-000-11076-0)supported by the Basic Research Program of the Korea Science and Engineering FoundationProjectsupported by the 2007 Hongik University Research Fund,Korea
文摘The formabilityof AZ31 sheet begins to increase drastically at 150℃.The incremental forming technique was thus applied to AZ31 sheet at 150℃to utilize the formability to its fullest capacity at the lowest possible temperature for forming applications.A surface scanning technique was used followed by the tool path generation to incrementally form an egg surface.After thorough examination of various tool paths,the surface was most successfully produced by forming an intermediate shape followed by a series of tool paths.Flexible scale stickers were devised to improve the accuracy in the measurement of grid deformation.
基金Project(50504019) supported by the National Natural Science Foundation of ChinaProject(2008BB4040) supported by the Science Foundation of Chongqing, ChinaProject(2008AA4028) supported by Scientific and Technological Project of Chongqing Science and Technology Commission, China
文摘Repeatedly unidirectional bending(RUB) was applied to the magnesium alloy sheet to improve the basal texture.The effect of RUB temperature on resulting structure and room temperature properties was investigated.The texture components of the sheet undergoing RUB at recovery temperature were similar to those of the sheet undergoing RUB at room temperature(RT).As the RUB temperature increased to above recrystallization temperature,the texture components became more disperse and the pyramidal components increased.With the increase of RUB temperature,the grain size near the surface of the sheets undergoing RUB tended to grow up.When the sheets were processed by RUB at medium-high temperature followed by annealing at 533 K,the yield strength and fracture elongation were lower than those of the cold rolled sheet;however,the Erichsen value was slightly higher than that of the cold rolled sheet.The sheet undergoing RUB at RT followed by annealing at 533 K represented the best mechanical properties.
文摘Equal channel angular pressing (ECAP) processing and annealing were applied to the AZ31 magnesium alloy sheets to evaluate the potential improvement in the mechanical properties and formability. The ECAP experiment was conducted at 300 ℃ in a die having an included angle of 90o between two channels by the BCZ route with the sheets rotated by 90°about the normal axis of plate plane. The tensile tests and conical cup tests were conducted at various temperatures from 20 to 250 ℃. The experimental results indicated that improving the working temperatures could lead to the soft in the material and the enhancement of ductility. Comparatively, the ECAPed AZ31 alloy sheets showed the lower yield strength and smaller conical cup value (CCV) than the unECAPed counterpart in the room temperature. The difference in yield strength between them became small in the elevated temperature, but the ECAPed samples still had the smaller CCV value, implying the improved formability. The texture of the AZ31 alloy sheets could be modified by ECAP and the decrease in the yield strength and more uniform deformation realized in the material, so the formability of AZ31 alloy sheets was improved.
基金Project(2006 BAE04B02-3) supported by the National Scientific and Technological Support Program during the 11th Five-year Plan of China
文摘The evolution of texture during the annealing and hot rolling process of extruded AZ31 magnesium alloy sheets was studied. There are two kinds of texture components in the extruded AZ31 sheets. One is {0002}<1010> and the other is {1010}<1120>. The {0002}<1010>component predominates. After annealing at 723 K for 3 h, both {0002}<1010> and {1010}<1120> components are strengthened moderately. This indicates that grains with both two components mentioned above grow faster than those with other orientations. The {1010}<1120> component disappears and the intensity of {0002}<1010> component decreases significantly after hot rolling with a 30% reduction at 623 K. This is mainly attributed to rotational dynamic recrystallization (RDX) during the hot rolling.
文摘Microstructures, tensile properties, fracture characteristics of commercial AZ31 magnesium alloy thin sheet were studied by optical microscopy, scanning electron microscopy and uniaxial tensile test. Tensile tests were carried out at room temperature and 473K, with strain rates of 8.3×10 -44.2×10 -3s -1. The results show that grain refinement effects are better at high temperature, and it increases with the decrease of strain rate at 473K. Compared with that tested at room temperature, no apparent uniform plastic deformation stage exists in the stress—strain curves tested at 473K; afterwards, the stress—strain curve presents wavelike downward under condition of the small strain rate. Yield strength and tensile strength of the alloy decrease drastically while the elongation increases greatly. With the increase of strain rate, yield strength and tensile strength of the alloy increase, but the elongation decreases. The fracture of the alloy tested at room temperature is quasi-cleavage failure and ductile failure at 473K.
基金Project(50504019)supported by the National Natural Science Foundation of ChinaProject(2008BB4040)supported by the Science Foundation of Chongqing,ChinaProject(2008AA4028)supported by Scientific and Technological Project of Chongqing Science and Technology Commission,China
文摘Electric product house of magnesium alloy sheet is usually obtained by warm stamping owing to its poor plasticity and formability at room temperature.The formability of AZ31B magnesium alloy sheet can be improved by repeated unidirectional bending(RUB)process through control of(0002)basal texture.Compared with as-received sheet,the Erichsen value(IE)of the sheet underwent RUB process increases to 5.90 from 3.53 at room temperature.It is also confirmed that cell phone houses could be stamped successfully in crank press with AZ31B magnesium alloy sheets underwent RUB process.It provides an alternative to the electronics industry in the application of magnesium alloys.
基金This work was camied out as a collaborative research program supportld by General Motors and Institute of Metal Research.
文摘A high-ductility ZME200(Mg–2.3Zn–0.4Mn–0.2Ce^(1))alloy was newly developed for vehicle closure and structure applications,based on an earlier ZE20(Mg–2.0Zn–0.2Ce)alloy for extrusion applications.Previous study indicates that the hot deformation behavior of as-cast ZME200 alloy varies with processing parameters,namely temperature and strain rate.In this follow-up study,a conventional rolling process was optimized to obtain magnesium sheets with a very fine grain structure and high ductility.The microstructure,mechanical properties,and corrosion resistances of ZME200 alloy were investigated,and compared with those of commercial AZ31 magnesium alloy.It was demonstrated that the ZME200 alloy sheet exhibits extraordinarily higher ductility(36%in tensile elongation),much superior stretch formability(an Erichsen value of 9.5),lower anisotropy,comparable strength and corrosion resistance to AZ31 alloy.The unique RD–TD double split texture with remarkably reduced intensity and grain refinement gives rise to the significantly improved ductility and formability at room-temperature.
基金funded by the Program of Energy Research and Development(PERD)of Natural Resources Canada
文摘Twin roll casting was commercialized for a strip production from ferrous and non-ferrous alloys in the 1950 s;however,its application to magnesium has proven difficult and still creates major challenges.This report describes global efforts in expanding manufacturing capabilities of magnesium sheet through twin roll casting path,offering many benefits,including a reduction in number of processing steps and energy savings.In addition to hardware design,alloy transformation during processing,product microstructure and properties,examples of successful solutions along with present technology and knowledge limitations are discussed.A particular attention is paid to developments at Canmet MATERIALS,having the only in North America pilot scale twin roll casting facility,devoted to magnesium.Efforts are described that aim at design of new magnesium alloys,which could take advantage of unique processing conditions during twin roll casting and contribute to the overall progress in magnesium sheet manufacturing.
基金financially supported by the Czech Science Foundation(grant No.19-22604S)the Operational Program Research,Development and Education,The Ministry of Education,Youth,and Sports(OP RDE,MEYS)(grant No.CZ.02.1.01/0.0/0.0/16_013/0001794)。
文摘The deformation behavior of the Mg-Al-Mn sheet was investigated during tensile loading along the rolling(RD)and transversal direction(TD)with special attention to the early stage of deformation.The activity of dislocation slip systems during the transition from elastic to plastic deformation was revealed by the acoustic emission(AE)technique.The parametrization and statistical AE analysis using the adaptive sequential k-mean(ASK)clustering provided necessary information about the individual deformation mechanisms and their evolution.The AE findings were supported by microstructural analyses,including in-situ secondary electron(SE)imaging and Schmid factor estimation for the activity of particular dislocation slip systems with respect to the loading direction.It was found that basal slip is the dominating mechanism up to the stress of~80 MPa in both loading directions with an absolute dominance during the RD-loading,while during the TD-loading,the contribution of prismatic slip to the deformation at stresses above 50 MPa was determined.Below the yielding in both loading directions,the predominance of prismatic over pyramidal slip was found at the stress in the range of 80-110 MPa and the opposite tendency occurred at stresses between 110 and 140 MPa.
文摘The microstructures and mechanical properties of hot rolled AZ31 Mg alloy sheets were studied to understand the microstrucrure evolution during AZ31 Mg alloy hot rolling process. The roller was heated to 180℃with burning hydrogen, and the extruded plates were rolled at 400℃from 10 to 1 mm with a reduction of 30% in thickness per pass. The result shows that there is no side-cracking of these rolled sheets every pass. The extruded microstructures are greatly refined and mechanical properties are improved. The fine grains of about 4μm were obtained of the final 0.9 mm sheets.
文摘A comprehensive consideration based on castability or plastic formability, as well as mechanical properties for development of either cast magnesium alloys or wrought magnesium alloys is a very important issue. To develop new magnesium alloy sheets with high formability at room temperature, the microstructure, texture, ductility and anisotropy of rolled Mg-Zn-Gd alloy sheets were investigated. The sheets exhibit an excellent ultimate elongation of nearly 50% and an uniform elongation greater than 30% with a very low planar anisotropy. The new sheet has a random basal texture and the basal pole is tilted by maximum 40° from the normal direction towards the transverse direction. The majority of grains in the tilted texture have an orientation favorable for both basal slip and tensile twining because of their high Schmid factor. The low planar anisotropy, the large uniform elongations and the high strain hardening rate observed in the Mg-Zn-Gd sheets result in excellent room temperature formability, the Erichsen values reach ~8, well comparable with the conventional aluminum alloys sheets at room temperature. The solidification pathways and phase equilibria of Mg-Al-Ca alloys have been profoundly investigated by using thermal analysis and thermodynamic calculations. The relationship between hot tearing tendency and alloy compositions were discussed in terms of strength of the mushy zone, solidification pathways and feeding mechanisms, et al. Thixoforming refers to as that metal components are formed in their semi-solid state. Criteria for thixoforming are summarized and then the thixoformability of Mg-Al-Ca based alloys (AC alloys) are evaluated using the thermodynamic calculations based on the consideration of metallurgical parameters.
文摘Zn-Mg alloy coatings were obtained by physical vapor deposition (PVD) on electroplated steel sheets. Study on the formation of intermetallic phases in the coatings was conducted through the use of X-ray diffraction (XRD) ,scanning electron microscope (SEM) and glow discharge optical emission spectrometry (GDOES). It is found that MgZn2 is the main Zn-Mg alloy phase formed after heat treatment. The formation of Mg-Zn intermetallic phases is controlled not only by thermodynamics, but also by kinetics. MgZn2 has different morphologies, such as laminar structure,porous structure and floc-like structure,which are mainly determined by the annealing temperature. Obvious diffusion of Mg starts at 350 ℃, and the diffusion of iron increases significantly when the temperature is elevated to 380℃.
基金the National Natural Science Foundation of China(Nos.51704209,U1810208,U1810122)the Central Government Guided Local Science and Technology Development Projects,China(No.YDZJSX2021A010)+5 种基金the Projects of International Cooperation in Shanxi Province,China(Nos.201803D421086,201903D421076)Shanxi Province Patent Promotion Implementation Fund,China(No.20200718)the Technological Innovation Programs of Higher Education Institutions in Shanxi Province,China(No.201802034)Shanxi Province Scientific Facilities and Instruments Shared Service Platform of Magnesium-based Materials Electric Impulse Aided Forming,China(No.201805D141005)Science and Technology Major Project of Shanxi Province,China(Nos.20191102008,20191102007,20181101008)Yantai High-end Talent Introduction“Double Hundred Plan”,China(2021)。