采用无坩埚感应熔炼超声气体雾化法(electrode induction melting gas atomization,EIGA)制备了Inconel 718预合金粉末,并利用SEM对合金粉末进行了表征,通过预合金粉末热等静压工艺制备了Inconel 718粉末合金坯料并测试了力学性能.研究结果表明,镍基合金Inconel 718易于制得化学成分满足要求的洁净粉末,但热等静压过程中碳化物形成元素扩散至粉末表面,并以氧化物为核心生成包含Ti和Nb的碳化物以及Ni3Nb的硬质薄膜,形成粉末高温合金的原始颗粒边界(prior particle boundaries,PPBs),使粉末合金的塑性、韧性和持久性能低于锻造合金.通过后续工艺抑制或消除热等静压过程中产生的原始颗粒边界可显著提升材料的综合力学性能.
Abstract
Inconel 718 alloy,with outstanding high-temperature resistance and mechanical proper-ties,has been widely used in aviation fields.However,large and complex structural components are diffi-cult to produce by traditional processes,which may lead to segregation,micropores,and Laves phases.Net-shape hot isostatic pressing(HIP)is a powder metallurgy processing technology that produces near-shape or net-shape components with the desired microstructures,properties,and cost effectiveness.In this study,Inconel 718 pre-alloyed powder was prepared using the electrode induction melting gas atomi-zation technique,and then the pre-alloyed powder was characterized.Powder compacts were prepared by the HIP of the pre-alloyed powder,and their mechanical properties were tested.Although clean,high-quality powder can be obtained from Inconel 718 alloy due to its lower chemical reactivity compared to ti-tanium alloys,carbide-forming elements diffuse to the powder surface during HIP.These form a hard film with the original oxide particles as nuclei,consisting of Ni3Nb and carbides of Ti and Nb.These films be-come prior particle boundaries(PPBs)in the obtained powder metallurgy Inconel 718 alloy,resulting in lower ductility,toughness,and stress rupture life than those of the wrought version of the alloy.Suppress-ing the formation of the PPBs during HIP or eliminating them via subsequent processing significantly im-proves the comprehensive mechanical properties of the material.
维普
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