Compressive anisotropy of extruded Mg-2Dy-0.5Zn （mole fraction, %） alloy sheet was investigated. The alloy sheet was mainly composed ofα-Mg, （Mg, Zn）xDy phase and a large number of long period stacking ordered （...Compressive anisotropy of extruded Mg-2Dy-0.5Zn （mole fraction, %） alloy sheet was investigated. The alloy sheet was mainly composed ofα-Mg, （Mg, Zn）xDy phase and a large number of long period stacking ordered （LPSO） phases distributed along the extrusion direction. The compressive experimental results show that the alloy sheet exhibits an obvious compressive anisotropy. The compressive strength of the specimen in the extrusion direction （ED） is higher than those of the specimens in the transverse direction （TD） and 45° inclined to the extrusion direction. The compressive yield strength （CYS）, ultimate compressive strength （UCS） and compressive strain of the specimen in the ED are 274.65 MPa, 518.94 MPa and 12.93%, respectively. The compressive anisotropy is mainly attributed to the distribution of LPSO phase and formation of〈10 10〉//ED fiber texture in the deformed grains.展开更多
Microstructure evolution and corrosion properties of Mg-2Dy-0.5Zn （at.%） alloy during cooling after solution treatment were investigated. The microstructure of alloy in the solid solution state （530 oC, 12 h） was ...Microstructure evolution and corrosion properties of Mg-2Dy-0.5Zn （at.%） alloy during cooling after solution treatment were investigated. The microstructure of alloy in the solid solution state （530 oC, 12 h） was composed ofα-Mg and small amounts of （Mg, Zn）xDy phases. During cooling at a cooling rate of 2 oC/min, the 14H-type LPSO phase gradually precipitated in the grain inte-rior and its volume fraction increased with increasing cooling time. The alloy cooled for 20 min exhibited the highest hardness value. In addition, electrochemical and immersion test results indicated that the alloy cooled for 5 min exhibited small corrosion current and low corrosion rate. The good corrosion resistance of alloy was mainly attributed to the continuous distribution of LPSO phase along the grain boundary.展开更多
Microstructural evolution and age-hardening behavior of Mg-2 Dy-6 Zn(at%)alloy during solid-solution and aging treatment were investigated.The microstructure of as-cast alloy is composed of a-Mg,Mg3 DyZn6(Ⅰ)phase,Mg3...Microstructural evolution and age-hardening behavior of Mg-2 Dy-6 Zn(at%)alloy during solid-solution and aging treatment were investigated.The microstructure of as-cast alloy is composed of a-Mg,Mg3 DyZn6(Ⅰ)phase,Mg3 Dy2 Zn3(W)phase,Mg(Zn,Dy)phase and a small amount of Mg0.97Zn0.03 phases.After solid-solution treatment(480℃,12 h),all the I phases and most W phases dissolve into a-Mg matrix and the remainder W phases transform into Mg(Dy,Zn)phase and MgDy3 phase.During aging treatment,I phase and small amounts of W phases co-precipitate from α-Mg matrix,respectively.The alloy exhibits a peak hardness of HV 77.5 at 200 ℃ for 8 h.The excellent age-hardening behavior of alloy is mainly attributed to the co-precipitation strengthening of I and W phases.展开更多
The microstructure and texture development in a Mg-0.41Dy(wt%)alloy after plane strain compression(PSC)at 300℃under a strain rate of 10^(-2)and 10^(-4)s^(-1),up a final true strain of—1.2 were investigated using ele...The microstructure and texture development in a Mg-0.41Dy(wt%)alloy after plane strain compression(PSC)at 300℃under a strain rate of 10^(-2)and 10^(-4)s^(-1),up a final true strain of—1.2 were investigated using electron backscatter diffraction(EBSD)and X-ray diffraction.At high strain rate of 10^(-2)s^(-1),the microstructure exhibited massive twins mainly{101^(-)2}extension,{1011}contraction and{101^(-)3}-{101^(-)2}double twin due to the random texture of the as-cast alloy.Meanwhile,at a low strain rate of 10^(-4)s^(-1),the microstructure was characterized by dynamic recrystallization at the{101^(-)2}extension,(101^(-)1)contraction twins and grain boundaries.Twin dynamic recrystallization(TDRX),rotational dynamic recrystallization(RDRX)and discontinuous dynamic recrystallization(DDRX)were the main mechanisms responsible for the formation of recrystallized grains.The texture was characterized by the formation of three fibers:basal<0001>,<101^(-)0>//CD and<112^(-)0>//CD where CD is the compression direction.Moreover,the texture was less sensitive to the deformation conditions since the recrystallized grains showed the same orientation than twins.The changes of the mechanical properties of the alloy were ascribed to the resulting microstructure due to the twinning and dynamic recrystallization.展开更多
Microstructure and mechanical properties of an extruded Mg-2Dy-0.5Zn （at.%） alloy during isothermal ageing at 180℃ were investigated. Microstructure of the as-extruded alloy is mainly composed of α-Mg phase, 14H l...Microstructure and mechanical properties of an extruded Mg-2Dy-0.5Zn （at.%） alloy during isothermal ageing at 180℃ were investigated. Microstructure of the as-extruded alloy is mainly composed of α-Mg phase, 14H long period stacking order （LPSO） phase and small amounts of （Mg, Zn）=Dy particle phases. During ageing, the 14H LPSO phase forms and develops and its volume fraction increases with increasing ageing time. Tensile test showed that the peak-aged alloy exhibits similar yield and ultimate tensile strengths and elongation to failure at room temperature, 100℃ and 200℃, but excellent elevated temperature strengths at 300℃ as compared to the as-extruded and over-aged alloys. The analysis showed that the excellent elevated temperature strengths of the peak-aged alloy are attributed to the LPSO phase strengthening and the grain refinement strengthening, and the role of the LPSO strengthening is related to not only its amount, but also its morphology.展开更多
Age hardening characteristic and tensile property of Mg-3.5Dy-4.0Gd-3.1Nd-0.4Zr alloy were investigated. The alloy exhibits a considerable age hardening effect up to 250℃. Increasing the aging temperature leads to a ...Age hardening characteristic and tensile property of Mg-3.5Dy-4.0Gd-3.1Nd-0.4Zr alloy were investigated. The alloy exhibits a considerable age hardening effect up to 250℃. Increasing the aging temperature leads to a shorter aging time to reach the peak hardness and a lower peak hardness. The tensile results show that the peak-aged specimens have higher tensile strength at the temperature below 200℃. However, with the increase of temperature further, the tensile strength decreases dramatically and elongation increases drastically. The loss in tensile strength and increase in elongation at high temperature are possibly associated with the instability of secondary precipitates. The fracture mechanism of alloy transfers from intergranular to transgranular with the increase of experimental temperature.展开更多
Mg87-xCuxDy13（x=22,27,32） bulk metallic glasses （BGMs） with a diameter of 6-8 mm and in-situ Mg phase reinforced Mg70Cu17Dy13 BMG matrix composite with a diameter of 3 mm have been prepared by copper mould casting...Mg87-xCuxDy13（x=22,27,32） bulk metallic glasses （BGMs） with a diameter of 6-8 mm and in-situ Mg phase reinforced Mg70Cu17Dy13 BMG matrix composite with a diameter of 3 mm have been prepared by copper mould casting. The glass forming ability （GFA） of Mg-Cu-Dy alloys have been investigated by differential scanning calorimetry （DSC） and X-Ray diffraction （XRD） and tne mechanical properties have been measured. Results show that Mg87-xCuxDy13（x=22,27,32） alloys in the Mg-Cu-Dy alloy system exhibit excellent GFA, and Mg60Cu27Dy13 alloy has the largest GFA among these alloys. And In-situ Mg phase reinforced Mg70Cu17Dy13 BMG matrix composite exhibits some work hardening and a high fracture compressive strength of 702.38 MPa and some plastic strain of 0.81%. The improvement of the mechanical properties is attributed to the fact that the Mg phase distributed in the amorphous matrix of the alloy has some effective load bearing and plastic deformation ability to restrict the expanding of shear bands and cracks and produce its own plastic deformation.展开更多
基金Projects(51301082,51464031,51201158)supported by the National Natural Science Foundation of China
文摘Compressive anisotropy of extruded Mg-2Dy-0.5Zn （mole fraction, %） alloy sheet was investigated. The alloy sheet was mainly composed ofα-Mg, （Mg, Zn）xDy phase and a large number of long period stacking ordered （LPSO） phases distributed along the extrusion direction. The compressive experimental results show that the alloy sheet exhibits an obvious compressive anisotropy. The compressive strength of the specimen in the extrusion direction （ED） is higher than those of the specimens in the transverse direction （TD） and 45° inclined to the extrusion direction. The compressive yield strength （CYS）, ultimate compressive strength （UCS） and compressive strain of the specimen in the ED are 274.65 MPa, 518.94 MPa and 12.93%, respectively. The compressive anisotropy is mainly attributed to the distribution of LPSO phase and formation of〈10 10〉//ED fiber texture in the deformed grains.
基金Project supported by the National Natural Science Foundation of China(51301082,51464031)Natural Science Foundation of Shanxi Province(2015011038)
文摘Microstructure evolution and corrosion properties of Mg-2Dy-0.5Zn （at.%） alloy during cooling after solution treatment were investigated. The microstructure of alloy in the solid solution state （530 oC, 12 h） was composed ofα-Mg and small amounts of （Mg, Zn）xDy phases. During cooling at a cooling rate of 2 oC/min, the 14H-type LPSO phase gradually precipitated in the grain inte-rior and its volume fraction increased with increasing cooling time. The alloy cooled for 20 min exhibited the highest hardness value. In addition, electrochemical and immersion test results indicated that the alloy cooled for 5 min exhibited small corrosion current and low corrosion rate. The good corrosion resistance of alloy was mainly attributed to the continuous distribution of LPSO phase along the grain boundary.
基金financially supported by the National Natural Science Foundation of China(Nos.51301082 and51464031)
文摘Microstructural evolution and age-hardening behavior of Mg-2 Dy-6 Zn(at%)alloy during solid-solution and aging treatment were investigated.The microstructure of as-cast alloy is composed of a-Mg,Mg3 DyZn6(Ⅰ)phase,Mg3 Dy2 Zn3(W)phase,Mg(Zn,Dy)phase and a small amount of Mg0.97Zn0.03 phases.After solid-solution treatment(480℃,12 h),all the I phases and most W phases dissolve into a-Mg matrix and the remainder W phases transform into Mg(Dy,Zn)phase and MgDy3 phase.During aging treatment,I phase and small amounts of W phases co-precipitate from α-Mg matrix,respectively.The alloy exhibits a peak hardness of HV 77.5 at 200 ℃ for 8 h.The excellent age-hardening behavior of alloy is mainly attributed to the co-precipitation strengthening of I and W phases.
基金the PRFU national project under Grant Agreement No.B00L02UN280120180005.
文摘The microstructure and texture development in a Mg-0.41Dy(wt%)alloy after plane strain compression(PSC)at 300℃under a strain rate of 10^(-2)and 10^(-4)s^(-1),up a final true strain of—1.2 were investigated using electron backscatter diffraction(EBSD)and X-ray diffraction.At high strain rate of 10^(-2)s^(-1),the microstructure exhibited massive twins mainly{101^(-)2}extension,{1011}contraction and{101^(-)3}-{101^(-)2}double twin due to the random texture of the as-cast alloy.Meanwhile,at a low strain rate of 10^(-4)s^(-1),the microstructure was characterized by dynamic recrystallization at the{101^(-)2}extension,(101^(-)1)contraction twins and grain boundaries.Twin dynamic recrystallization(TDRX),rotational dynamic recrystallization(RDRX)and discontinuous dynamic recrystallization(DDRX)were the main mechanisms responsible for the formation of recrystallized grains.The texture was characterized by the formation of three fibers:basal<0001>,<101^(-)0>//CD and<112^(-)0>//CD where CD is the compression direction.Moreover,the texture was less sensitive to the deformation conditions since the recrystallized grains showed the same orientation than twins.The changes of the mechanical properties of the alloy were ascribed to the resulting microstructure due to the twinning and dynamic recrystallization.
基金Projects(52001152, 51961021) supported by the National Natural Science Foundation of ChinaProjects(DC2020353, DC2020342, DC2022017, DC2022025, DC2022027) supported by the Undergraduate Innovation and Entrepreneurship Training Programs,China。
基金supported by the National Natural Science Foundation of China (Grant No.50771049)
文摘Microstructure and mechanical properties of an extruded Mg-2Dy-0.5Zn （at.%） alloy during isothermal ageing at 180℃ were investigated. Microstructure of the as-extruded alloy is mainly composed of α-Mg phase, 14H long period stacking order （LPSO） phase and small amounts of （Mg, Zn）=Dy particle phases. During ageing, the 14H LPSO phase forms and develops and its volume fraction increases with increasing ageing time. Tensile test showed that the peak-aged alloy exhibits similar yield and ultimate tensile strengths and elongation to failure at room temperature, 100℃ and 200℃, but excellent elevated temperature strengths at 300℃ as compared to the as-extruded and over-aged alloys. The analysis showed that the excellent elevated temperature strengths of the peak-aged alloy are attributed to the LPSO phase strengthening and the grain refinement strengthening, and the role of the LPSO strengthening is related to not only its amount, but also its morphology.
文摘本文研究了铸态、固溶态和时效过程的Mg-1.67at.%Zn-2.3at.%Dy与Mg-1.51at.%Zn-2.77at.%Er合金的微观结构变化及其力学性能的影响。微观分析结果表明,Mg-1.67at.%Zn-2.3at.%Dy与Mg-1.51at.%Zn-2.77at.%Er合金,在493 K温度下时效20 h硬度均达到峰值,峰值硬度分别为106.4 HV和98.7 HV。拉伸试验结果表明,固溶处理后,合金Mg-1.67at.%Zn-2.3at.%Dy与Mg-1.51at.%Zn-2.77at.%Er的抗拉强度均有明显的提高。合金Mg-1.67at.%Zn-2.3at.%Dy固溶后包含三个相,分别是α-Mg相,Mg8Zn Dy共晶相,Mg12Zn Dy LPSO相(包括14H型和18R型)。合金Mg-1.51at.%Zn-2.77at.%Er固溶后包含三个相,分别是α-Mg相,Mg3Zn3Er2共晶相,Mg12Zn Er LPSO相(包括14H型和18R型)。
文摘Age hardening characteristic and tensile property of Mg-3.5Dy-4.0Gd-3.1Nd-0.4Zr alloy were investigated. The alloy exhibits a considerable age hardening effect up to 250℃. Increasing the aging temperature leads to a shorter aging time to reach the peak hardness and a lower peak hardness. The tensile results show that the peak-aged specimens have higher tensile strength at the temperature below 200℃. However, with the increase of temperature further, the tensile strength decreases dramatically and elongation increases drastically. The loss in tensile strength and increase in elongation at high temperature are possibly associated with the instability of secondary precipitates. The fracture mechanism of alloy transfers from intergranular to transgranular with the increase of experimental temperature.
基金Funded by the National Natural Youth Science Foundation of China (No.50901038)
文摘Mg87-xCuxDy13（x=22,27,32） bulk metallic glasses （BGMs） with a diameter of 6-8 mm and in-situ Mg phase reinforced Mg70Cu17Dy13 BMG matrix composite with a diameter of 3 mm have been prepared by copper mould casting. The glass forming ability （GFA） of Mg-Cu-Dy alloys have been investigated by differential scanning calorimetry （DSC） and X-Ray diffraction （XRD） and tne mechanical properties have been measured. Results show that Mg87-xCuxDy13（x=22,27,32） alloys in the Mg-Cu-Dy alloy system exhibit excellent GFA, and Mg60Cu27Dy13 alloy has the largest GFA among these alloys. And In-situ Mg phase reinforced Mg70Cu17Dy13 BMG matrix composite exhibits some work hardening and a high fracture compressive strength of 702.38 MPa and some plastic strain of 0.81%. The improvement of the mechanical properties is attributed to the fact that the Mg phase distributed in the amorphous matrix of the alloy has some effective load bearing and plastic deformation ability to restrict the expanding of shear bands and cracks and produce its own plastic deformation.
