摘要
The high-temperature oxidation resistance of the nickel superalloy prepared by the laser powder bed fusion(LPBF)has been significantly increased as a result of in-situ formation of a thermal barrier layer(α-Al_(2)O_(3)+CaMoO4)during oxidative annealing of surface layers modified by electric spark treatment(EST).The reactive EST of the LPBF-built items based on nickel EP741NP alloy was carried out with low-melting Al−12%Si,Al−6%Ca−0.6%Si and Al−7%Ca−1%Mn electrodes.It was found that under EST done by Al−7%Ca−1%Mn electrode an intermetallic(β-NiAl+γ'-Ni3Al)15μm-thick layer reinforced by spherical oxide(CaMe)O nanoparticles was formed.Formation of that structure increases the wear resistance of LPBF nickel superalloy by 4.5 times.Further oxidative annealing at 1000°C leads to a formation of continuous two-layered coating with an inner layer ofα-Al_(2)O_(3) and an outer layer of CaMoO4,which together act as an effective barrier preventing the diffusion of oxygen into the bulk of the superalloy.
采用电火花处理(EST)对激光粉末床熔融(LPBF)制备的镍基高温合金表面进行改性,由于在氧化退火过程中合金的表面原位形成了热障层(α-Al_(2)O_(3)+CaMoO4),从而显著提高了其高温抗氧化性能。使用低熔点的Al−12%Si、Al−6%Ca−0.6%Si和Al−7%Ca−1%Mn电极材料,对基于EP741NP镍基合金的LPBF样品进行EST处理。结果发现,当采用Al−7%Ca−1%Mn电极进行EST处理时,形成了厚约15μm的球形氧化物(CaMe)O纳米颗粒增强金属间化合物(β-NiAl+γ'-Ni3Al)层。该结构的形成使LPBF镍基高温合金的耐磨性提高了4.5倍。进一步在1000℃下进行氧化退火,合金表面形成了连续的双层涂层,其内层为α-Al_(2)O_(3),外层为CaMoO4。这两层共同作用,可有效阻止氧气向合金体内扩散。
基金
supported by the Ministry of Science and Higher Education of the Russian Federation under State Research Assignment(No.0718-2020-0034)
Development Program of MISIS(No.K7-2023-009)within the Framework Strategic Academic Leadership Program"Priority-2030".
