Abstract
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.
基金项目
国家自然科学基金(52271149)
国家自然科学基金(51971123)
国家自然科学基金(51925103)
Innovation Program of Shanghai Municipal Education Commission(2021-01-07-00-09-E00114)
Program 173(2020-JCIQ-ZD-186-01)
高等学校学科创新引智计划(111计划)(D16002)
Space Utilization System of China Manned Space Engineering(KJZ-YY-NCL08)
Singapore Ministry of Education Academic Research Funds(MOE-T2EP50120-0010)
Singapore Ministry of Education Academic Research Funds(MOE-T2EP50220-0010)
Singapore Ministry of Education Academic Research Funds(A-8001225-00-00)
China Scholarship Council(CSC)Scholarship,China(CSC 202106890047)
NETL
NSTL
万方数据