Gadolinium(Gd)is one of the most effective strengthening elements for magnesium alloys.The development of commercially available Mg-Gd alloys with high Gd content and the optimization of their preparation processes ha...Gadolinium(Gd)is one of the most effective strengthening elements for magnesium alloys.The development of commercially available Mg-Gd alloys with high Gd content and the optimization of their preparation processes have been a major focus in magnesium alloy research.In this study,a Mg-23Gd-2Zn-0.4Zr alloy with ultra-high Gd content is designed,and high-quality fabrication is achieved using laser-directed energy deposition(LDED)technology.Through heat treatment and microstructure control,a balance between tensile strength(425 MPa)and elongation(3.4%)is achieved.The ultra-high strength of the LDED-T6 VZ232K alloy is primarily attributed to precipitation strengthening caused by the ultra-high density(2.4×10^(4)μm^(-2))ofβphase.The high ductility is mainly due to the modification of the fracture mode,facilitated by the introduction of a substantial number of stacking fault structures during solution heat treatment.The extended hardness plateau(exceeding 138 Hv)and high yield strength(exceeding 300 MPa)are associated with the three-directional cross-interlocked structure of theβphase in the over-aged state at 220℃ and 250℃.The analysis of the LDED-VZ232K alloy indicates that reduced heat input during the additive manufacturing(AM)process is critical for the defect-free fabrication of alloys with ultra-high Gd content.展开更多
Lightweight aluminum(Al)alloys have been widely used in frontier fields like aerospace and automotive industries,which attracts great interest in additive manufacturing(AM)to process high-value Al parts.As a mainstrea...Lightweight aluminum(Al)alloys have been widely used in frontier fields like aerospace and automotive industries,which attracts great interest in additive manufacturing(AM)to process high-value Al parts.As a mainstream AM technique,laser-directed energy deposition(LDED)shows good scalability to meet the requirements for large-format component manufacturing and repair.However,LDED Al alloys are highly challenging due to their inherent poor printability(e.g.low laser absorption,high oxidation sensitivity and cracking tendency).To further promote the development of LDED high-performance Al alloys,this review offers a deep understanding of the challenges and strategies to improve printability in LDED Al alloys.The porosity,cracking,distortion,inclusions,element evaporation and resultant inferior mechanical properties(worse than laser powder bed fusion)are the key challenges in LDED Al alloys.Processing parameter optimizations,in-situ alloy design,reinforcing particle addition and field assistance are the efficient approaches to improving the printability and performance of LDED Al alloys.The underlying correlations between processes,alloy innovation,characteristic microstructures,and achievable performances in LDED Al alloys are discussed.The benchmark mechanical properties and primary strengthening mechanism of LDED Al alloys are summarized.This review aims to provide a critical and in-depth evaluation of current progress in LDED Al alloys.Future opportunities and perspectives in LDED high-performance Al alloys are also outlined.展开更多
基金financially supported by the National Key Research and Development Pragram of China(Grant No.2023YFB4603300)。
文摘Gadolinium(Gd)is one of the most effective strengthening elements for magnesium alloys.The development of commercially available Mg-Gd alloys with high Gd content and the optimization of their preparation processes have been a major focus in magnesium alloy research.In this study,a Mg-23Gd-2Zn-0.4Zr alloy with ultra-high Gd content is designed,and high-quality fabrication is achieved using laser-directed energy deposition(LDED)technology.Through heat treatment and microstructure control,a balance between tensile strength(425 MPa)and elongation(3.4%)is achieved.The ultra-high strength of the LDED-T6 VZ232K alloy is primarily attributed to precipitation strengthening caused by the ultra-high density(2.4×10^(4)μm^(-2))ofβphase.The high ductility is mainly due to the modification of the fracture mode,facilitated by the introduction of a substantial number of stacking fault structures during solution heat treatment.The extended hardness plateau(exceeding 138 Hv)and high yield strength(exceeding 300 MPa)are associated with the three-directional cross-interlocked structure of theβphase in the over-aged state at 220℃ and 250℃.The analysis of the LDED-VZ232K alloy indicates that reduced heat input during the additive manufacturing(AM)process is critical for the defect-free fabrication of alloys with ultra-high Gd content.
基金supported by the 2022 MTC Young Individual Research Grants(Grant No.M22K3c0097)the Singapore Research,Innovation and Enterprise(RIE)2025 PlanSingapore Aerospace Programme Cycle 16(Grant No.M2215a0073)。
文摘Lightweight aluminum(Al)alloys have been widely used in frontier fields like aerospace and automotive industries,which attracts great interest in additive manufacturing(AM)to process high-value Al parts.As a mainstream AM technique,laser-directed energy deposition(LDED)shows good scalability to meet the requirements for large-format component manufacturing and repair.However,LDED Al alloys are highly challenging due to their inherent poor printability(e.g.low laser absorption,high oxidation sensitivity and cracking tendency).To further promote the development of LDED high-performance Al alloys,this review offers a deep understanding of the challenges and strategies to improve printability in LDED Al alloys.The porosity,cracking,distortion,inclusions,element evaporation and resultant inferior mechanical properties(worse than laser powder bed fusion)are the key challenges in LDED Al alloys.Processing parameter optimizations,in-situ alloy design,reinforcing particle addition and field assistance are the efficient approaches to improving the printability and performance of LDED Al alloys.The underlying correlations between processes,alloy innovation,characteristic microstructures,and achievable performances in LDED Al alloys are discussed.The benchmark mechanical properties and primary strengthening mechanism of LDED Al alloys are summarized.This review aims to provide a critical and in-depth evaluation of current progress in LDED Al alloys.Future opportunities and perspectives in LDED high-performance Al alloys are also outlined.
