首页|Abnormal mechanochemical effect in ultraprecision machining of an additively manufactured precipitation-strengthened high-entropy alloy

Abnormal mechanochemical effect in ultraprecision machining of an additively manufactured precipitation-strengthened high-entropy alloy

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Recently,researchers have explored the use of precipitation strengthening and finer microstructures with high-density dislocations in additive manufacturing to produce high-entropy alloys(HEAs)with ad-justable properties.However,the inherent surface roughness and lack of machinability research in AMed HEAs limit their engineering applications.In this study,we systematically investigated the microstruc-tural characteristics,mechanical properties,and machinability of Fe29.3Co28.7Ni28.6Al6.8Ti6.6(at.％)HEAs with three different structures:single FCC phase cellular(SPC),dual precipitation-strengthened(DPS),and single precipitation-strengthened(SPS).These structures were fabricated by selective laser melting and isothermally annealing at 780 and 940 ℃.Compared to SPC HEA,DPS HEA exhibits a significant in-crease in yield strength and ultimate tensile strength but with a dramatic sacrifice in ductility.SPS HEA exhibits similar mechanical properties to SPC HEA due to the pronounced coarsening of L21 precipitates.The ultraprecision machining micro-cutting test showed that SPC HEA had a significant mechanochem-ical effect,as evidenced by a sharp drop in cutting force for inked workpieces,but not DPS HEA.An abnormal finding was that the negligible reflection of cutting force for SPS HEAs suggested a negative mechanochemical effect,even though SPS HEA had equally excellent plasticity like SPC HEA.It was found that nanocrystallization-induced strength enhancement and ductility reduction of SPS HEA lead to chips'deformation dominated by shear avalanche rather than chip folding of SPC HEA,which involves the re-duction of surface energy and friction of chips'interfaces.Overall,these results and our research findings may guide the machining of AMed precipitation-strengthened HEAs and accelerate their engineering ap-plication.

High-entropy alloySelective laser meltingPrecipitation strengtheningMachinabilityMechanochemical effect

Long Xu、Yuchao Bai、Yunfa Guo、Chang Ren、Xiaohua Tan、Yandong Jia、Gang Wang、Hao Wang

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Institute of Materials,Shanghai University,Shanghai 200444,China

Zhejiang Institute of Advanced Materials,Shanghai University,Jiashan 314100,China

Department of Mechanical Engineering,National University of Singapore,Singapore 117575,Singapore

国家自然科学基金国家自然科学基金国家自然科学基金Innovation Program of Shanghai Municipal Education CommissionProgram 173高等学校学科创新引智计划(111计划)Space Utilization System of China Manned Space EngineeringSingapore Ministry of Education Academic Research FundsSingapore Ministry of Education Academic Research FundsSingapore Ministry of Education Academic Research FundsChina Scholarship Council(CSC)Scholarship,China

5227114951971123519251032021-01-07-00-09-E001142020-JCIQ-ZD-186-01D16002KJZ-YY-NCL08MOE-T2EP50120-0010MOE-T2EP50220-0010A-8001225-00-00CSC 202106890047

2024

10.1016/j.jmst.2023.05.045

材料科学技术(英文版)
中国金属学会 中国材料研究学会 中国科学院金属研究所

材料科学技术(英文版)

CSTPCD
影响因子：0.657
ISSN：1005-0302
年,卷(期)：2024.170(3)
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