Simultaneous grain refinement and nanoscale spinodal decomposition of β phase in Ti-Nb-Ta-Zr alloy induced by ultrasonic mechanical impacts

Kheradmandfard, Mehdi,Kashani-Bozorg, Seyed Farshid,Kang, Kyeong-Hee,Penkov, Oleksiy V.,Zarei Hanzaki, Abbas,Pyoun, Young-Shik,Amanov, Auezhan,Kim, Dae-Eun Elsevier 2018 JOURNAL OF ALLOYS AND COMPOUNDS Vol.738 No.-

<P><B>Abstract</B></P> <P>It was found that ultrasonic nanocrystal surface modification (UNSM) treatment performed on Ti-Nb-Ta-Zr (TNTZ) alloy surface to produce a gradient nanostructured surface layer also resulted in the nano-scale spinodal decomposition of β phase. For the first time, nano-scale spinodal decomposition of β phase induced by ultrasonic mechanical impacts was observed in a short time without any age treatment. The peak shift of XRD to lower angles, (110) β XRD peak splitting, overlapped and asymmetric XRD peaks, satellite reflections in the SAED pattern, and lattice straining in HR-TEM images confirmed nano-scale spinodal decomposition of β phase in the TNTZ alloy induced by UNSM treatment. Nano-scale EDS line-scan probe analysis revealed the β phase separation into nano-scale domains of Ti-rich (β<SUB>1</SUB>) and Ti-depleted (β<SUB>2</SUB>) phases. HR-TEM images showed the semi-coherent arrangement of Ti-rich (β<SUB>1</SUB>) and Ti-depleted (β<SUB>2</SUB>) regions. Nanosized grain formation and spinodal decomposition of β phase were induced simultaneously by UNSM treatment. The nano-scale grains, high dislocation density, and semi-coherent interface between the spinodally separated phases contributed to the high hardness of the UNSM-treated TNTZ alloy specimen.</P> <P><B>Highlights</B></P> <P> <UL> <LI> UNSM is a method that applies ultrasonic impacts to generate nanostructured surface. </LI> <LI> UNSM was applied to the surface of TNTZ alloy. </LI> <LI> Gradient nanostructured layer was produced in the top surface. </LI> <LI> Nano-scale spinodal decomposition of β phase induced by ultrasonic impacts. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Nanostructured β-type titanium alloy fabricated by ultrasonic nanocrystal surface modification

Kheradmandfard, Mehdi,Kashani-Bozorg, Seyed Farshid,Kim, Chang-Lae,Hanzaki, Abbas Zarei,Pyoun, Young-Shik,Kim, Jung-Hyong,Amanov, Auezhan,Kim, Dae-Eun Elsevier 2017 Ultrasonics sonochemistry Vol.39 No.-

<P><B>Abstract</B></P> <P>The surface of β-type Ti-Nb-Ta-Zr (TNTZ) alloy, which is a promising material for biomedical applications, was treated with the ultrasonic nanocrystal surface modification (UNSM) technique to enhance its hardness. As a result, a gradient nanostructured (GNS) layer was generated in the surface; the microstructure of the top surface layer consisted of nanoscale lamellae with a width of about 60–200nm. In addition, there were lamellar grains consisting of nanostructured subgrains having unclear and wavy boundaries. The treated surface exhibited a hardness value of ∼385HV compared to 190HV for the untreated alloy. It was further determined that highly dense deformation twins were generated at a depth of ∼40–150µm below the UNSM-treated surface. These deformation twins led to a significant work hardening effect which aided in enhancing the mechanical properties. It was also found that UNSM treatment resulted in the formation of micropatterns on the surface, which would be beneficial for high bioactivity and bone regeneration performance of TNTZ implants.</P> <P><B>Highlights</B></P> <P> <UL> <LI> UNSM is a method that utilizes ultrasonic vibration to generate nanostructured surface. </LI> <LI> The surface of β-type Ti-Nb-Ta-Zr (TNTZ) alloy was treated with the UNSM technique. </LI> <LI> A gradient nanostructured layer was generated in the surface. </LI> <LI> Top surface layer consisted of nanoscale lamellae with a width of about 60–200nm. </LI> <LI> Hardness of treated surface was ∼385HV compared to 190HV for the untreated alloy. </LI> </UL> </P>

Significant improvement in cell adhesion and wear resistance of biomedical β-type titanium alloy through ultrasonic nanocrystal surface modification

Kheradmandfard, Mehdi,Kashani-Bozorg, Seyed Farshid,Lee, Jung Seung,Kim, Chang-Lae,Hanzaki, Abbas Zarei,Pyun, Young-Sik,Cho, Seung-Woo,Amanov, Auezhan,Kim, Dae-Eun Elsevier 2018 JOURNAL OF ALLOYS AND COMPOUNDS Vol.762 No.-

<P><B>Abstract</B></P> <P>A novel β-type Ti–29Nb–13Ta–4.6Zr (TNTZ) alloy with a low Young's modulus, high bio-corrosion resistance, and excellent biocompatibility has been recently introduced for implant applications. Here, ultrasonic nanocrystal surface modification (UNSM) treatment was applied to TNTZ alloy to improve its wear resistance and biofunctionality. Application of UNSM to a TNTZ alloy resulted in the generation of a nanostructured surface layer. The wear resistance of the UNSM-treated specimen was observed to be more than 7 times higher than that of the untreated one. Cell culture tests indicated that MC3T3 cells adhered and spread more readily on the UNSM-treated specimen than on the untreated one. MTT assays after 1 and 4 days in culture also indicated enhancement of cell proliferation on the UNSM-treated specimen than that of the untreated one. Live/dead assay revealed no significant cytotoxicity in either substrate. The significant improvement of cell adhesion, spreading, and proliferation on the UNSM-treated TNTZ alloy specimen were attributed to both grain refinement and micro-patterned surface effects. These results demonstrate that UNSM-treatment not only improves the wear resistance of TNTZ alloy, but also enhances its biocompatibility, which makes it a strong candidate for applications in medical implants.</P> <P><B>Highlights</B></P> <P> <UL> <LI> UNSM treatment was applied to a β titanium alloy to generate nanostructured surface. </LI> <LI> The wear resistance of the UNSM-treated specimen was significantly improved. </LI> <LI> Treated specimens showed significant improvement of cell adhesion and proliferation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Mechanical and Microstructural Characterization of Hybrid Aluminum Nanocomposites Synthesized from an Al–Fe3O4 System by Friction Stir Processing

Ghasem AzimiRoeen,Seyed Farshid Kashani‑Bozorg,Martin Nosko,Saeid Lotfian 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.9

Reactive friction stir processing was used to fabricate in situ hybrid nano-composite. Nano-sized Al2O3and Al13Fe4productswere formed in the stir zone of rolled AA1050 through the addition of pre-milled Al + Fe3O4 powder mixture. Thethermomechanical phenomena associated with the process and addition of active powder mixture provided the occurrenceof the aluminothermy reaction. Microstructural investigations showed significant matrix grain refinement; the mean grainsize of ~ 3 μm was achieved. The nano-sized reinforcement products prevented grain growth after dynamic recrystallizationprocess by pinning the grain boundaries. The excellent matrix grain refining and formation of in situ hard reinforcementsled to the increase of hardness and tensile strength to ~ 56% and 49% over those of the untreated substrate, respectively.

Effect of Pre- and Post-weld Heat Treatment on Microstructure and Mechanical Properties of GTD-111 Superalloy Welds

Morteza Taheri,Ayyub Halvaee,Seyed Farshid Kashani‑Bozorg 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.5

In this paper, the liquation cracking and strain-age cracking behavior of nickel-based GTD-111 superalloy which is weldedby Nd:YAG pulse laser through several heat treatment cycles, has been studied. The effort was to develop the most suitablemicrostructure concerning shape, morphology and γʹ phase volume fraction by several different heat treatment cycles inorder to obtain a weld without any defects. The results revealed that γʹ, γ–γʹ eutectic, MC carbide, Boride enriched withCr–Mo, and Ni–Zr intermetallic phase are the most important parameters in the formation of grain boundary melt and cracksin HAZ in casting conditions. Before welding, a full solution heat treatment resulted in the omission of liquation cracking,which attributed to full solution of boride and Ni–Zr intermetallic phases, and the solution treatment of a high percentageeutectic phases, and γʹ. Investigations on the hardness of the base metal showed that there was a direct relationship betweenhardness of the base metal and crack length. In such case, as the hardness of the base metal increases, it’s not only added toabsorption of more welding stresses, but also stress release decreased, which resulted in the expansion of cracking in HAZ.Added to this, aging treatment of samples which were undergone aging treatment before welding, resulted in the formationof strain-age cracking due to γʹ phase precipitation.

Rational hybrid modulation of P, N dual-doped holey graphene for high-performance supercapacitors

Nazarian-Samani, Masoud,Haghighat-Shishavan, Safa,Nazarian-Samani, Mahboobeh,Kim, Myeong-Seong,Cho, Byung-Won,Oh, Si-Hyoung,Kashani-Bozorg, Seyed Farshid,Kim, Kwang-Bum Elsevier Sequoia 2017 Journal of Power Sources Vol. No.

<P><B>Abstract</B></P> <P>A P, N dual-doped holey graphene (PNHG) material is prepared by a scalable, facile synthetic approach, using a mixture of glucose, dicyandiamide (DCDA), and phosphoric acid (H<SUB>3</SUB>PO<SUB>4</SUB>). H<SUB>3</SUB>PO<SUB>4</SUB> successfully functions as an “acid catalyst” to encourage the uniform breakage of C=C bonds to create large, localized perforations over the graphene monolith. Further acid treatment and annealing introduce in-plane holes. The correlation between the capacitance of the PNHG and its structural parameters during the fabrication process is comprehensively evaluated. A thermally induced sp<SUP>2</SUP>→sp<SUP>3</SUP> transformation occurs at high temperatures because of the substantial loss of graphitic sp<SUP>2</SUP>-type carbons, together with a dramatic reduction in capacitance. The target PNHG-400 electrode material delivers exceptionally high gravimetric capacitance (235.5 F g<SUP>−1</SUP> at 0.5 A g<SUP>−1</SUP>), remarkable rate capability (84.8% at 70 A g<SUP>−1</SUP>), superior capacitance retention (93.2 and 92.7% at 10 and 50 A g<SUP>−1</SUP> over 25000 cycles, respectively), and acceptable volumetric capacitance due to moderate density, when it is used with organic electrolytes in the voltage range between 0 and 3 V. These results suggest a pioneering defect-engineered strategy to fabricate dual-doped holey graphene with valuable structural properties for high-performance electric double layer supercapacitors, which could be used in next-generation energy storage applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Rationally designed P, N dual-doped holey graphene as an electrode in supercapacitors. </LI> <LI> Importance of synergistic ion transport with a high content of C=C bonds. </LI> <LI> Occurrence of sp<SUP>2</SUP>→sp<SUP>3</SUP> transition in graphene structure at temperatures higher than 400 °C. </LI> <LI> High capacitance, excellent rate capability and cyclic stability of the target PNHG-400. </LI> <LI> Novel approach to develop future supercapacitors with high energy and power densities. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Fabrication of well-designed defect-laden holey graphene counterparts for energy-related applications using a simple, up-scalable and cost-effective strategy.</P> <P>[DISPLAY OMISSION]</P>

Strong, persistent superficial oxidation-assisted chemical bonding of black phosphorus with multiwall carbon nanotubes for high-capacity ultradurable storage of lithium and sodium

Haghighat-Shishavan, Safa,Nazarian-Samani, Masoud,Nazarian-Samani, Mahboobeh,Roh, Ha-Kyung,Chung, Kyung-Yoon,Cho, Byung-Won,Kashani-Bozorg, Seyed Farshid,Kim, Kwang-Bum The Royal Society of Chemistry 2018 Journal of Materials Chemistry A Vol.6 No.21

<P>We report a new composite of black phosphorus and multiwall carbon nanotubes (BP-CNT) prepared <I>via</I> a surface oxidation-assisted chemical bonding procedure. The controlled air exposure successfully changed the naturally hydrophobic BP powder to the desired hydrophilicity, which was found indispensable to stable bond formation between the BP and the functionalized CNTs during ball milling. The BP-CNT composites were further fabricated into anodes for both Li- and Na-ion batteries, using a sodium carboxyl methyl cellulose-poly(acrylic acid) (NaCMC-PAA) binary polymeric binder. The hydrophilicity of BP also played a very important role in forming strong bonds with the hydroxyl groups of NaCMC and the carboxylic acid groups of PAA. The plausible mechanisms of stable bond formation were comprehensively examined, and the results revealed two types of strong connections: P-O-C bonds and dehydration cross links. Consequently, the material delivered outstanding electrochemical performance in the anode, with a high discharge capacity of 1681 mA h g<SUP>−1</SUP> after 400 cycles at a current density of 0.2C (1C = 2596 mA g<SUP>−1</SUP>) for Li-ion batteries. It also successfully delivered a first discharge capacity of 2073 and 850 mA h g<SUP>−1</SUP> at 0.2C and 2C for Na-ion batteries, respectively, with excellent capacity retentions at both rates after 200 cycles. These salient results, which originated from the modified hydrophilic BP, will give further impetus to explore BP-based composites for use as high-performance materials for advanced energy storage applications.</P>

A robust design of Ru quantum dot/N-doped holey graphene for efficient Li-O2batteries

Nazarian-Samani, Masoud,Lim, Hee-Dae,Haghighat-Shishavan, Safa,Kim, Hyun-Kyung,Ko, Youngmin,Kim, Myeong-Seong,Lee, Suk-Woo,Kashani-Bozorg, Seyed Farshid,Abbasi, Majid,Guim, Hwan-Uk,Kim, Dong-Ik,Roh, K The Royal Society of Chemistry 2017 Journal of Materials Chemistry A Vol.5 No.2

<P>Herein, we report a simple, versatile, defect-engineered method to fabricate Ru quantum dots (Ru QDs) uniformly anchored on a nitrogen-doped holey graphene (NHG) monolith. It uses<I>in situ</I>pyrolysis of mixed glucose, dicyandiamide (DCDA), and RuCl3, followed by an acid treatment, and a final heat treatment to introduce in-plane holes of various sizes. A novel transmission method in scanning electron microscopy was successfully implemented to directly visualize the holes with color contrast. A low accelerating voltage of 5 kV enabled prolonged observation without significant electron beam damage. The mechanisms of hole creation were examined in detail using various characterization techniques as well as control experiments. The Ru QDs had significant catalytic activity and resulted in larger in-plane holes through the graphene sheets. The mechanical strain and the chemical reactivity of Ru QDs significantly diminished the activation energy barrier for the oxidation of CC bonds in the graphene structure. The Ru QD/NHG hybrid material was utilized as an electrocatalyst for the oxygen evolution reaction in Li-O2batteries, showing much lower charge overpotentials compared to the bare NHG counterpart. The defect-laden holey graphene counterpart can be highly functionalized for multiple applications, leading to a new method of nanoengineering based on atomic scale defects.</P>