FABRICATION OF FE-CR-AL-ODS (OXIDE DISPERSION STRENGTHENING) FERRITIC ALLOY THROUGH POWDER METALLURGY PROCESS

• Main Author: Permana, Bayu
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/50810
• Institution: Institut Teknologi Bandung

The ferritic alloy FeCrAl-ODS (oxide dispersion strengthening) is an alloy that has a ferritic solid solution matrix with addition of oxide particle dispersion (ODS) to the alloy matrix to obtain better properties. This alloy has a good properties of radiation resistance, high temperature corrosion and oxidation resistance, and creep resistance. Therefore, the ferritic alloy FeCrAl-ODS could be potential to be used in industry and technology, one of which is as a cladding material in nuclear reactors. However, conventional processing lines such as casting has a difficulty to obtain oxide particles (ODS) homogeneously dispersed on the alloy matrix. Therefore, this study aims to make FeCrAl-ODS alloys through a powder metallurgy process, then investigate the quality of the ferritic alloy FeCrAl-ODS produced and determine the effect of ODS addition on the properties of ferritic alloys. In addition, this study also aims to determine the response of ferritic alloys produced through this powder metallurgy process to embrittlement at a temperature of 475 ?, also the alloy's response to high temperatures, that is high temperature oxidation and thermal shock. The FeCrAl-ODS alloy was synthesized through dry milling process using a Planetary Ball Mill (PBM) with a rotation speed of 1000 rpm for 5 hours, and a weight ratio of balls and powders is 10:1. Then, it is continued with the compacting and sintering processes, where the sintering process is carried out in an atmosphere which is added with reducing gas H2 and inert gas Ar. The characterization and testing carried out were the Charpy impact testing, Rockwell hardness testing, compressive testing, microstructure observation with a light optical microscope (LOM) and scanning electron microscope (SEM), electron dispersion mapping. spectroscopy (EDS-Mapping) to investigate the composition and its homogeneity and the level of homogeneity of ODS particle dispersion, as well as knowing the phase formed in the alloy by x-ray diffraction (XRD). In this research, two variations of Fe20Cr20Al and Fe20Cr20Al-0.5Y2O3 alloys have been successfully made, which have a single phase ferritic solid solution with ODS particles homogeneously dispersed in the alloy matrix, but there is still a fairly severe segregation of the composition. The results of the mechanical properties testing showed that the Fe20Cr20Al alloy with addition of 0.5wt% Y2O3 (ODS) had a higher compressive strength, that was 191.71 MPa compared to the Fe20Cr20Al alloy without ODS, that was 150.11 MPa. The response of the Fe20Cr20Al-0.5Y2O3 alloy to high temperatures was also better than the Fe20Cr20Al alloy, where the Fe20Cr20Al-0.5Y2O3 alloy had a low oxidation rate of 349.58 g2/cm4s and good resistance to thermal shock, while the Fe20Cr20Al alloy had high oxidation rate of 1227.2 g2/cm4s and poor thermal shock resistance. Then, the aging process at a temperature of 475? for 64 hours caused the alloy to experience embrittlement, which was indicated by a decreasing in the impact energy per area of the Fe20Cr20Al-0.5Y2O3 alloy, from 5.00 j/cm2 to 1.95 /cm2, and the Fe20Cr20Al alloy. decreased from 4.88 j/cm2 to 2.08 j/cm2