Estudo do efeito da adição de pentóxido de nióbio na microestrutura e propriedades do aço Eurofer processado pela metalurgia do pó
EUROFER is the reference steel for manufacturing structural components used in nuclear fusion reactors. It is a reduced activity ferritic-martensitic (RAFM) stainless steel, with has its good mechanical strength, corrosion resistance, creep resistance, and reduced radioactive activity, as well as...
محفوظ في:
| المؤلف الرئيسي: | |
|---|---|
| مؤلفون آخرون: | |
| التنسيق: | doctoralThesis |
| اللغة: | pt_BR |
| منشور في: |
Universidade Federal do Rio Grande do Norte
|
| الموضوعات: | |
| الوصول للمادة أونلاين: | https://repositorio.ufrn.br/handle/123456789/56512 |
| الوسوم: |
إضافة وسم
لا توجد وسوم, كن أول من يضع وسما على هذه التسجيلة!
|
| الملخص: | EUROFER is the reference steel for manufacturing structural components used in nuclear
fusion reactors. It is a reduced activity ferritic-martensitic (RAFM) stainless steel, with
has its good mechanical strength, corrosion resistance, creep resistance, and reduced
radioactive activity, as well as a low ductile-to-brittle transition temperature. However,
being a stainless steel, it cannot operate at temperatures exceeding 500 °C, as
microstructural changes occur, leading to material embrittlement. Studies have been
conducted to mitigate this issue, and the solution was to strengthen the steel through oxide
dispersion strengthening (ODS) with yttrium oxide processed via powder metallurgy
(PM). The objective of this work is to contribute to the development of new EUROFERbased alloys with the addition of niobium pentoxide (Nb2O5) processed by PM using highenergy milling (HEM) and sintering via Spark Plasma Sintering (SPS). Pure EUROFER chips were milled in a high-energy ball mill for different times (5h, 10h, and 15h), both with and without the addition of Nb2O5 (0%wt., 3%wt., 5%wt., and 7%wt.) over the same time intervals. The powders were sintered via SPS and conventional furnace (CF). The
effects of milling time and Nb2O5 concentration, as well as sintering methods, on the
physical, mechanical, and magnetic properties of the sintered materials were analyzed.
The results showed that increasing the milling time reduced the average particle size
distribution by 57% and improved the sinterability of the milled powders. X-ray
diffraction (XRD) and magnetic analyses of the powders with added Nb2O5 suggest a new
composition of the steel's solid solution. XRD analyses of SPS-sintered samples reveal
the formation of retained martensitic and austenitic phases. The microhardness of the
alloys obtained from pure EUROFER chips sintered by SPS (≈ 560 HV) was higher than
those sintered by CF (≈ 65 HV) and the as-received bar (410 HV). The addition of Nb2O5
to the steel maintained the microhardness of samples sintered via SPS in the same order
of magnitude as the bar, while those sintered via CF exhibited lower values (≈ 78 HV).
Furthermore, the densities of the samples sintered via SPS were higher than those sintered
via CF. Given the presented results, the production of these new alloys holds promise for
developing new materials with lower density and higher hardness compared to the initial
EUROFER alloy. |
|---|