Ti-xNb alloys produced by laser powder bed fusion(LPBF)from mixed powder usually exhibit an inhomogeneous elemental distribution,leading to a deterioration in mechanical properties.To address this issue,we proposed a ...Ti-xNb alloys produced by laser powder bed fusion(LPBF)from mixed powder usually exhibit an inhomogeneous elemental distribution,leading to a deterioration in mechanical properties.To address this issue,we proposed a strategy to achieve heterostructure in laser powder bed fused Ti-xNb alloys from mixed powders through precipitation ofωwithinβ.Moreover,the effect of Nb content on the micro structure and mechanical behavior of Ti-xNb alloys was studied.The results indicated that in-situ laser re-melting can realize the homogeneous elemental distribution in Ti-xNb alloys.When the Nb content increases from 30 wt%,35 wt%to40 wt%,Ti-xNb alloys experience a transformation from β+α' to β+ω and monolithic β.Specifically,ωnano-precipitates in Ti-35Nb alloy are only distributed in some β grains,forming a heterostructure with“softβ”and“hard β+ω”grains.As a result,LPBF-produced Ti-35Nb alloy demonstrates excellent mechanical properties,with yield strength of ^(792±6)MPa,tensile strength of ^(806±7)MPa,Young's modulus of ^(68±6)GPa,and uniform elongation of ^(18.0±1.1)%.The Frank-Read mechanism induces dislocation proliferation and dislocation cross-slip,and the geometrically necessary dislocations(GNDs)are induced at the heterogeneous interface of“softβ”and“hard β+ω”grains,resulting in an enhancement in the strength-ductility synergy of Ti-35Nb alloy produced by LPBF.This work provides an innovative strategy to improve the strength-ductility synergy of LPBF-produced Ti-xNb alloys from mixed powders by tailoring ω nano-precipitates.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.92166112,52373236 and 52271132)the Natural Science Foundation of Guangdong Province(Grant No.2024A1515010658)+6 种基金the Guangdong Province International Science and Technology Cooperation Project(Grant No.2023A0505050103)the Guangxi Key Laboratory of Information Materials(Grant No.231033-K)the Open Project Program of Wuhan National Laboratory for Optoelectronics(Grant No.2021WNLOKF010)Guangzhou Science and Technology Planning Project(2024A04J9966)Guangdong Provincial Science and Technology Plan Project(2022A0505050043)The financial support from the ECU industrial grant(No.G1006320)ECU DVC strategic research fund(project number 23965)。
文摘Ti-xNb alloys produced by laser powder bed fusion(LPBF)from mixed powder usually exhibit an inhomogeneous elemental distribution,leading to a deterioration in mechanical properties.To address this issue,we proposed a strategy to achieve heterostructure in laser powder bed fused Ti-xNb alloys from mixed powders through precipitation ofωwithinβ.Moreover,the effect of Nb content on the micro structure and mechanical behavior of Ti-xNb alloys was studied.The results indicated that in-situ laser re-melting can realize the homogeneous elemental distribution in Ti-xNb alloys.When the Nb content increases from 30 wt%,35 wt%to40 wt%,Ti-xNb alloys experience a transformation from β+α' to β+ω and monolithic β.Specifically,ωnano-precipitates in Ti-35Nb alloy are only distributed in some β grains,forming a heterostructure with“softβ”and“hard β+ω”grains.As a result,LPBF-produced Ti-35Nb alloy demonstrates excellent mechanical properties,with yield strength of ^(792±6)MPa,tensile strength of ^(806±7)MPa,Young's modulus of ^(68±6)GPa,and uniform elongation of ^(18.0±1.1)%.The Frank-Read mechanism induces dislocation proliferation and dislocation cross-slip,and the geometrically necessary dislocations(GNDs)are induced at the heterogeneous interface of“softβ”and“hard β+ω”grains,resulting in an enhancement in the strength-ductility synergy of Ti-35Nb alloy produced by LPBF.This work provides an innovative strategy to improve the strength-ductility synergy of LPBF-produced Ti-xNb alloys from mixed powders by tailoring ω nano-precipitates.
