Microstructures and mechanical properties of mechanically alloyed and spark plasma sintered Al_0.3CoCrFeMnNi high entropy alloy

Pohan, Rizaldy M.,Gwalani, Bharat,Lee, Junho,Alam, Talukder,Hwang, J.Y.,Ryu, Ho Jin,Banerjee, Rajarshi,Hong, Soon Hyung Elsevier 2018 Materials chemistry and physics Vol.210 No.-

<P><B>Abstract</B></P> <P>The present study focuses on phase evolution in Al<SUB>0.3</SUB>CoCrFeMnNi high entropy alloys (HEAs) during mechanical alloying and after spark plasma sintering. Aluminium addition hardens and induces ordered precipitates in a soft <I>fcc</I> alloy based on CoCrFeMnNi. Mechanical alloying of the alloy powders resulted in a single <I>fcc</I> phase. However, ordered B2 precipitates and chromium carbide precipitates were observed after spark plasma sintering. Sintering temperature optimization was done and maximum densification and hardness were obtained at 900 °C. High compressive yield strength of 979 ± 20 MPa and compressive ductility of 39 ± 3% were observed for the SPS processed alloy. Significant contributions from grain boundary strengthening coupled with dispersion strengthening via carbides and B2 particles appear to be major contributors to alloy strengthening. These hard intermetallic particles not only keep the grain growth in check but also increase the cumulative (fcc + B2) strength of the material.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Al<SUB>0.3</SUB>CoCrFeMnNi high entropy alloy was prepared using Spark Plasma Sintering. </LI> <LI> Optimum density and grain size is obtained at 900 °C sintering temperature. </LI> <LI> Microstructure consisted of fcc matric, ordered bcc (B2) and chromium carbides. </LI> <LI> Alloy showed high compressive strength of 979 MPa and failure strain of 39%. </LI> </UL> </P>

Strengthening of Al_0.3CoCrFeMnNi-based ODS high entropy alloys with incremental changes in the concentration of Y₂O₃

Gwalani, Bharat,Pohan, Rizaldy M.,Waseem, Owais Ahmed,Alam, Talukder,Hong, Soon Hyung,Ryu, Ho Jin,Banerjee, Rajarshi Elsevier 2019 Scripta materialia Vol.162 No.-

<P><B>Abstract</B></P> <P>The high-entropy alloy (HEA) composite Al<SUB>0.3</SUB>CoCrFeMnNi based on the face-centered-cubic (FCC) system and reinforced with 0–3 vol% Y<SUB>2</SUB>O<SUB>3</SUB> was processed by mechanical alloying followed by spark plasma sintering (SPS). The compressive yield strength of the Al<SUB>0.3</SUB>CoCrFeMnNi high-entropy alloy (HEA) increased phenomenally, from 0.98 GPa (0 vol% Y<SUB>2</SUB>O<SUB>3</SUB>) to 1.76 GPa (3 vol% Y<SUB>2</SUB>O<SUB>3</SUB>). A quantitative analysis by atom probe tomography (APT) suggested the in-situ formation of complex oxide resulting from the reaction of Y<SUB>2</SUB>O<SUB>3</SUB> with the HEA matrix during processing, enhancing the strength. Using the dispersion-barrier hardening model, the strengthening by dispersoids in Al<SUB>0.3</SUB>CoCrFeMnNi with Y<SUB>2</SUB>O<SUB>3</SUB> was calculated, and closely matched the experimental results.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Viewpoint from Indonesia

Soendjojo, Agus,Pohan, Saut S. Medical Publications Korea 1985 Medical Progress Vol.7 No.1

Isonumber based Iso-Key Interchange Protocol for Network Communication

Dani, Mamta S.,Meshram, Akshaykumar,Pohane, Rupesh,Meshram, Rupali R. International Journal of Computer ScienceNetwork S 2022 International journal of computer science and netw Vol.22 No.2

Key exchange protocol (KEP) is an essential setup to secure authenticates transmission among two or more users in cyberspace. Digital files protected and transmitted by the encryption of the files over public channels, a single key communal concerning the channel parties and utilized for both to encrypt the files as well as decrypt the files. If entirely done, this impedes unauthorized third parties from imposing a key optimal on the authorized parties. In this article, we have suggested a new KEP term as isokey interchange protocol based on generalization of modern mathematics term as isomathematics by utilizing isonumbers for corresponding isounits over the Block Upper Triangular Isomatrices (BUTI) which is secure, feasible and extensible. We also were utilizing arithmetic operations like Isoaddition, isosubtraction, isomultiplication and isodivision from isomathematics to build iso-key interchange protocol for network communication. The execution of our protocol is for two isointegers corresponding two elements of the group of isomatrices and cryptographic performance of products eachother. We demonstrate the protection of suggested isokey interchange protocol against Brute force attacks, Menezes et al. algorithm and Climent et al. algorithm.

죽탄 및 죽초액 제조를 위한 대나무의 탄화특성 고찰

김희열(Hui Yeol Kim),양원(Won Yang),K. Ibik,H.G. Pohan 한국연소학회 2008 KOSCOSYMPOSIUM논문집 Vol.- No.-

The carbonization experiment for production of optimization of bamboo carbonizer was proceeded by using lab scale tube furnace. The species of the boom boo that were used are local bamboos from Dam Yang, Indonesian Andong and Petung. The interrelation of electric resistance, specific surface area and pH of bamboo vinegar has been researched. As a result of this work, the charcoal's electric resistance were about 0.4 ㏁, 9.4 Ω at 600℃ and 900℃. Throughout this research the electric resistance rose as temperature went higher. The specific surface area got a rise as carbonization temperature got higher and charcoal that has specific surface area more than 300 m2/g was made at 700℃. The pH of bamboo vinegar showed the fact that it was increased as carbonization temperature augmented. In consequence it was believed that appropriate carbonization temperature to produce optimal bamboo charcoal is about 850℃ and of bamboo vinegar is about 540℃.

죽탄 및 죽초액 제조를 위한 인도네시아산 및 국내산 대나무의 탄화특성 비교 연구

Yang, Won,Kim, Hui-Yeol,Chae, Tae-Young,Ibik, K.,Pohan, H.G. 한국연소학회 2010 한국연소학회지 Vol.15 No.1

Carbonization characteristics of Indonesian bamboos were investigated using lab-scale tube furnace, in order to find optimum design temperature of a carbonizer for producing bamboo charcoal and vinegar. The bamboo samples used in this study are local bamboos from Damyang in Korea, Andong and Petung in Indonesia. Correlation of electric resistance, specific surface area and pH of bamboo vinegar with pyrolysis temperature has been investigated. Electric resistance of the charcoal increased for higher pyrolysis temperature the specific surface area was also increased as carbonization temperature got higher. Charcoal which has specific surface area of over $300\;m^2/g$ could be produced at $700^{\circ}C$. pH of bamboo vinegar was decreased for highter carbonization temperature and vinegar under pH 3 could be produced for all bamboo samples. In this experimental condition, it was found that lower carbonization temperature is better for producing bamboo vinegar of high quality, while higher temperature is better for obtaining bamboo charcoal with larger surface.

죽탄 및 죽초액 제조를 위한 인도네시아산 및 국내산 대나무의 탄화특성 비교 연구

양원(Won Yang),김희열(Hui Yeol Kim),채태영(Taeyoung Chae),K. Ibik,H.G. Pohan 한국연소학회 2010 한국연소학회지 Vol.15 No.1

Carbonization characteristics of Indonesian bamboos were investigated using lab-scale tube furnace, in order to find optimum design temperature of a carbonizer for producing bamboo charcoal and vinegar. The bamboo samples used in this study are local bamboos from Damyang in Korea, Andong and Petung in Indonesia. Correlation of electric resistance, specific surface area and pH of bamboo vinegar with pyrolysis temperature has been investigated. Electric resistance of the charcoal increased for higher pyrolysis temperature the specific surface area was also increased as carbonization temperature got higher. Charcoal which has specific surface area of over 300 ㎡/g could be produced at 700℃. pH of bamboo vinegar was decreased for highter carbonization temperature and vinegar under pH 3 could be produced for all bamboo samples. In this experimental condition, it was found that lower carbonization temperature is better for producing bamboo vinegar of high quality, while higher temperature is better for obtaining bamboo charcoal with larger surface.

Subcutaneous Basidiobolomycosis: A Rare and Underdiagnosed but Curable Fungal Infection - A Case Report

Yoana Fransiska Wahyuning Christi,Irmadita Citrashanty,Yuri Widia,Sylvia Anggraeni,Linda Astari,Daniel Edbert,Arthur Pohan Kawilarang,Evy Ervianti 대한의진균학회 2023 대한의진균학회지 Vol.28 No.3

Basidiobolomycosis is a rare deep fungal infection caused by Basidiobolus ranarum and characterized by the development of swollen erythematous nodular lesions. Several azoles have been shown to be an effective treatment for this condition. Herein, we report a case of basidiobolomycosis that was initially misdiagnosed as a different disease and resolved after itraconazole medication. A 25-year-old man presented with a 2.5-year history of extensive swelling on his right arm, face, and neck. Initially, he was diagnosed with lipoma and scapular tuberculosis; however, no improvements were observed post-surgery and with tuberculosis medication. Histopathological examinations revealed giant cells, aseptate hyphae, and the Splendore-Hoeppli phenomenon. Fungal culture confirmed the isolate to be Basidiobolus ranarum. The patient was given oral itraconazole 200 mg twice daily, and the complete resolution was achieved after 25 months of treatment.