航空航天领域的发展亟需在超高温服役条件下具有优异力学性能的先进结构材料,近年来开发的难熔高熵合金(refractory high entropy alloys,RHEAs)虽具有应用前景,但仍面临着室温脆性及元素偏析等问题,对其制备工艺提出较大挑战。而增材...航空航天领域的发展亟需在超高温服役条件下具有优异力学性能的先进结构材料,近年来开发的难熔高熵合金(refractory high entropy alloys,RHEAs)虽具有应用前景,但仍面临着室温脆性及元素偏析等问题,对其制备工艺提出较大挑战。而增材制造技术在制备RHEAs方面具有抑制元素偏析、细化组织且可实现复杂形状构件制备等独特优势,具有广泛的研究潜力。本文从介绍增材制造RHEAs的主要技术方式出发,对增材制造RHEAs的微观结构、元素分布及相组成特征进行归纳并概述其室温和高温力学性能。针对增材制造RHEAs面临的开裂、孔隙等主要工艺挑战,对近年来的相应研究成果进行综述,并提出通过成分调控与晶界工程优化增材制造工艺的新思路。最后,本文对于未来通过增材制造技术引入晶界强化元素或高熵陶瓷强化相实现室温塑性与高温强度的进一步提升以及通过抑制开裂与残余应力实现大尺寸RHEAs复杂构件制备等方面进行展望。展开更多
With the continuous advancement of aerospace technology,ensuring the reliability of aerospace engines after testing is critical.While various methods exist for assessing fatigue life,non-destructive prediction based o...With the continuous advancement of aerospace technology,ensuring the reliability of aerospace engines after testing is critical.While various methods exist for assessing fatigue life,non-destructive prediction based on insitu X-ray diffraction(XRD)residual stress analysis remains underexplored—particularly for low-cycle fatigue in welded joints.This study proposes a novel approach that uses in-situ XRD to monitor residual stress evolution under fatigue and creep loading in gas tungsten arc welding(GTAW)joints of aerospace-grade austenitic stainless steel SUS321.Through metallographic observation,scanning electron microscopy(SEM),electron backscatter diffraction(EBSD),and in-situ XRD measurements,we demonstrate a strong correlation between longitudinal residual stress at the weld center and fatigue life.Under fatigue loading at 60%of the ultimate tensile strength(UTS),longitudinal residual stress transitions from tensile to compressive with increasing cycles,and fatigue fracture occurs once residual stress approaches base metal levels(∼0 MPa).In contrast,under creep loading,no clear trend in Y-direction residual stress was observed,limiting its utility for creep life prediction.This work establishes a reliable,non-destructive framework for evaluating the service life of welded aerospace components,offering a new methodology beyond conventional practices.展开更多
文摘航空航天领域的发展亟需在超高温服役条件下具有优异力学性能的先进结构材料,近年来开发的难熔高熵合金(refractory high entropy alloys,RHEAs)虽具有应用前景,但仍面临着室温脆性及元素偏析等问题,对其制备工艺提出较大挑战。而增材制造技术在制备RHEAs方面具有抑制元素偏析、细化组织且可实现复杂形状构件制备等独特优势,具有广泛的研究潜力。本文从介绍增材制造RHEAs的主要技术方式出发,对增材制造RHEAs的微观结构、元素分布及相组成特征进行归纳并概述其室温和高温力学性能。针对增材制造RHEAs面临的开裂、孔隙等主要工艺挑战,对近年来的相应研究成果进行综述,并提出通过成分调控与晶界工程优化增材制造工艺的新思路。最后,本文对于未来通过增材制造技术引入晶界强化元素或高熵陶瓷强化相实现室温塑性与高温强度的进一步提升以及通过抑制开裂与残余应力实现大尺寸RHEAs复杂构件制备等方面进行展望。
基金supported by the Fundamental Research Funds for the Central Universities,the Institute of Marine Equipment,the Shanghai Rising-Star Program of Science and Technology Commission of Shanghai Municipality(Grant No.23QA1404700)National Natural Science Foundation of China(Grant Nos.52475384,52505409)China Postdoctoral Science Foundation(Grant No.2024M761963).
文摘With the continuous advancement of aerospace technology,ensuring the reliability of aerospace engines after testing is critical.While various methods exist for assessing fatigue life,non-destructive prediction based on insitu X-ray diffraction(XRD)residual stress analysis remains underexplored—particularly for low-cycle fatigue in welded joints.This study proposes a novel approach that uses in-situ XRD to monitor residual stress evolution under fatigue and creep loading in gas tungsten arc welding(GTAW)joints of aerospace-grade austenitic stainless steel SUS321.Through metallographic observation,scanning electron microscopy(SEM),electron backscatter diffraction(EBSD),and in-situ XRD measurements,we demonstrate a strong correlation between longitudinal residual stress at the weld center and fatigue life.Under fatigue loading at 60%of the ultimate tensile strength(UTS),longitudinal residual stress transitions from tensile to compressive with increasing cycles,and fatigue fracture occurs once residual stress approaches base metal levels(∼0 MPa).In contrast,under creep loading,no clear trend in Y-direction residual stress was observed,limiting its utility for creep life prediction.This work establishes a reliable,non-destructive framework for evaluating the service life of welded aerospace components,offering a new methodology beyond conventional practices.
