Mechanism of discontinuous precipitation(DP) in AZ80 alloy was investigated by phase-orientation correlated characterization.The results show DPs nucleate by turning the original grain boundaries(GBs) as reaction fron...Mechanism of discontinuous precipitation(DP) in AZ80 alloy was investigated by phase-orientation correlated characterization.The results show DPs nucleate by turning the original grain boundaries(GBs) as reaction front(RF),and further driving the RF to realize their growth.The DPs regions retained the same orientations as their parent grains.The misorientation angle and rotation axis of RFs had strong influence on DPs nucleation.The low-angle GBs,twin boundaries(TBs) and the GBs with specific misorientation axis which are known as low energy and low mobility GBs can hardly initiate DPs.In addition,the TBs had a strong ability to inhibit the growth of DPs,but it should be noticed that the growth of DPs cannot be totally inhibited by TBs.DPs can engulf the twins when the growth direction is approximately parallel to the long axis of TBs.The inhibition behavior is related to the distribution of Al solute atoms near the RF,boundary interactions of the TBs and twin tips with the RF,and the morphology of the continuous precipitations within the twins.展开更多
An ultra-high strength and toughness as-cast Mg-10Gd-1.7Y-1Zn-0.5Zr(wt.%)alloy was prepared via special ultrasonic melt treatment,and the peak-aged(200℃for 48 h)ultimate tensile strength(UTS),yield strength(YS)and el...An ultra-high strength and toughness as-cast Mg-10Gd-1.7Y-1Zn-0.5Zr(wt.%)alloy was prepared via special ultrasonic melt treatment,and the peak-aged(200℃for 48 h)ultimate tensile strength(UTS),yield strength(YS)and elongation(EL)at room temperature reaches 430 MPa,324 MPa,and 13.6%,respectively.The ultrasonic treatment during semi-solid conditions refines the grains and hinders the growth of the divorced eutectic phases(α-Mg+Mg_(3)Gd)during casting.During the solution treatment,the refined Mg_(3)Gd phase suppresses the formation of cubic-shaped GdY phases and block 14H long period stacking structure(14H-LPSO)phases,and further increases solute concentration in the matrix.More solute atoms promote the growth ofβ′plates with an increased aspect ratio of 8:1,which can increase critical resolved shear stress(CRSS),YS and work hardening rate.It is that found the aspect ratio ofβ′plates are mainly responsible for the improvement in the strength of the alloy under the same composition and heat treatment conditions.展开更多
Texture control of wrought Mg alloys, particularly in rolled Mg alloy sheets, has been an important research topic for the past several decades because it has significant influence on stretch formability at room tempe...Texture control of wrought Mg alloys, particularly in rolled Mg alloy sheets, has been an important research topic for the past several decades because it has significant influence on stretch formability at room temperature. For Mg alloys, {10-12} twinning can be easily activated and causes a 86.3° lattice rotation. Thus, pre-twinning deformation is considered as an effective and low-cost method for texture control in wrought Mg and its alloys. Furthermore, it has been verified that texture control via pre-twinning deformation can remarkably improve stretch formability of rolled Mg alloy sheets. In this review, recent researches on texture control via twinning deformation and its influence on stretch formability will be critically reviewed. The main contents include the micro-mechanism and impact factors of control in twin-orientation, plastic processing techniques of pre-inducing twins and the application of pre-induced twins in improvement of stretch formability. Finally, further research directions on this field were proposed.展开更多
In this study,typical microstructural characteristics of a metastableβTi alloy(Ti–5Al–5Mo–5V–3Cr–1Fe)forged in a dual-phase region(strain of 54%at 820℃)were investigated in detail by the combined use of X-ray d...In this study,typical microstructural characteristics of a metastableβTi alloy(Ti–5Al–5Mo–5V–3Cr–1Fe)forged in a dual-phase region(strain of 54%at 820℃)were investigated in detail by the combined use of X-ray diff raction,energy dispersive spectroscopy,electron channeling contrast imaging and electron backscatter diff raction techniques.Results show that the microstructure of the forged alloy is composed of bulkαgrains,αplates andβmatrix.The bulkαgrains correspond to retained primaryαphase(αp,average grain size^2.4μm),while theαplates are secondaryαphase(αs,width^70 nm)precipitated from theβmatrix during air cooling.During forging,theβmatrix experiences dynamic recovery with many subgrains and signifi cant orientation gradients formed.Analyses of the orientation relationship between theαandβphases show that the Burgers orientation relationship is not maintained between someα_p andβphases,which should be related to thermal deformation-induced changes of their orientations.In contrast,all of theαs plates are found to maintain well the Burgers orientation relationship with theβphase.展开更多
基金supported by National Natural Science Foundation of China (52201107)Research Program of Chongqing Municipal Education Commission (KJQN202201151)Natural Science Foundation of Chongqing (CSTB2023NSCQ-MSX0067).
文摘Mechanism of discontinuous precipitation(DP) in AZ80 alloy was investigated by phase-orientation correlated characterization.The results show DPs nucleate by turning the original grain boundaries(GBs) as reaction front(RF),and further driving the RF to realize their growth.The DPs regions retained the same orientations as their parent grains.The misorientation angle and rotation axis of RFs had strong influence on DPs nucleation.The low-angle GBs,twin boundaries(TBs) and the GBs with specific misorientation axis which are known as low energy and low mobility GBs can hardly initiate DPs.In addition,the TBs had a strong ability to inhibit the growth of DPs,but it should be noticed that the growth of DPs cannot be totally inhibited by TBs.DPs can engulf the twins when the growth direction is approximately parallel to the long axis of TBs.The inhibition behavior is related to the distribution of Al solute atoms near the RF,boundary interactions of the TBs and twin tips with the RF,and the morphology of the continuous precipitations within the twins.
基金supported by the National Natural Science Foundation of China(U21A2048,U2037601,U2241231)the Guangdong Major Project of Basic and Applied Basic Research(2020B0301030006)+3 种基金the National Key Research and Development Program of China(2021YFB3701100)the Science and Technology Research Program of the Chongqing Municipal Education Commission(KJZD-K202201108,KJQN202201136)The Cultivation Project of CQUT for Research and Innovation Group(2023TDZ006)the Academician in Chongqing Leaded Guidance Project of Science and Technology Innovation(CSTB2023YSZX-JCX0006).
文摘An ultra-high strength and toughness as-cast Mg-10Gd-1.7Y-1Zn-0.5Zr(wt.%)alloy was prepared via special ultrasonic melt treatment,and the peak-aged(200℃for 48 h)ultimate tensile strength(UTS),yield strength(YS)and elongation(EL)at room temperature reaches 430 MPa,324 MPa,and 13.6%,respectively.The ultrasonic treatment during semi-solid conditions refines the grains and hinders the growth of the divorced eutectic phases(α-Mg+Mg_(3)Gd)during casting.During the solution treatment,the refined Mg_(3)Gd phase suppresses the formation of cubic-shaped GdY phases and block 14H long period stacking structure(14H-LPSO)phases,and further increases solute concentration in the matrix.More solute atoms promote the growth ofβ′plates with an increased aspect ratio of 8:1,which can increase critical resolved shear stress(CRSS),YS and work hardening rate.It is that found the aspect ratio ofβ′plates are mainly responsible for the improvement in the strength of the alloy under the same composition and heat treatment conditions.
基金financially supported by the National Natural Science Foundation of China (project No. 51601154)the National Natural Science Foundation of China (project No. 51871036)+2 种基金the Fundamental Research Funds for the Central Universities (project No. XDJK2019B003)the Chongqing Science and Technology Commission (cstc2017jcyj AX0012)China Postdoctoral Science Foundation (2018T110948)
文摘Texture control of wrought Mg alloys, particularly in rolled Mg alloy sheets, has been an important research topic for the past several decades because it has significant influence on stretch formability at room temperature. For Mg alloys, {10-12} twinning can be easily activated and causes a 86.3° lattice rotation. Thus, pre-twinning deformation is considered as an effective and low-cost method for texture control in wrought Mg and its alloys. Furthermore, it has been verified that texture control via pre-twinning deformation can remarkably improve stretch formability of rolled Mg alloy sheets. In this review, recent researches on texture control via twinning deformation and its influence on stretch formability will be critically reviewed. The main contents include the micro-mechanism and impact factors of control in twin-orientation, plastic processing techniques of pre-inducing twins and the application of pre-induced twins in improvement of stretch formability. Finally, further research directions on this field were proposed.
基金financially supported by the Technology Innovation and Application Demonstration Project of Chongqing(Grant No.cstc2018jszx-cyzdX0080)the Fundamental and Cutting-Edge Research Plan of Chongqing(Grant No.cstc2018jcyjAX0299)。
文摘In this study,typical microstructural characteristics of a metastableβTi alloy(Ti–5Al–5Mo–5V–3Cr–1Fe)forged in a dual-phase region(strain of 54%at 820℃)were investigated in detail by the combined use of X-ray diff raction,energy dispersive spectroscopy,electron channeling contrast imaging and electron backscatter diff raction techniques.Results show that the microstructure of the forged alloy is composed of bulkαgrains,αplates andβmatrix.The bulkαgrains correspond to retained primaryαphase(αp,average grain size^2.4μm),while theαplates are secondaryαphase(αs,width^70 nm)precipitated from theβmatrix during air cooling.During forging,theβmatrix experiences dynamic recovery with many subgrains and signifi cant orientation gradients formed.Analyses of the orientation relationship between theαandβphases show that the Burgers orientation relationship is not maintained between someα_p andβphases,which should be related to thermal deformation-induced changes of their orientations.In contrast,all of theαs plates are found to maintain well the Burgers orientation relationship with theβphase.
