This study focused on improving the phase stability and mechanical properties of yttria-stabilized zirconia (YSZ), commonly utilized in gas turbine engine thermal barrier coatings, by incorporating Gd₂O₃, Er₂O₃, and TiO₂. The addition of 3-valent rare earth elements to YSZ can reduce thermal conductivity and enhance phase stability while adding the 4-valent element TiO₂ can improve phase stability and mechanical properties. Sintered specimens were prepared with hot-press equipment. Phase analysis was conducted with X-ray diffraction (XRD), and mechanical properties were assessed with Vickers hardness equipment. The research results revealed that, except for Z10YGE10T, most compositions predominantly exhibited the t-phase. Increasing the content of 3-valent rare earth oxides resulted in a decrease in the monoclinic phase and an increase in the tetragonal phase. In addition, the t(400) angle decreased while the t(004) angle increased. The addition of 10 mol% of 3-valent rare-earth oxides discarded the t-phase and led to the complete development of the c-phase. Adding 10 mol% TiO₂ increased hardness than YSZ.

A Ni-Ti-B alloy powder prepared by mechanical alloying (MA) of individual Ni, Ti, and B components is examined with the aim of elucidating the phase transitions and crystallization during heat treatment. Ti and B atoms penetrating into the Ni lattice result in a Ni (Ti, B) solid solution and an amorphous phase. Differential thermal analysis (DTA) reveals peaks related to the decomposition of the metastable Ni (Ti, B) solid solution and the separation of equilibrium Ni₃Ti, TiB₂, and τ-Ni₂0Ti₃B₆ phases. The exothermal effects in the DTA curves move to lower temperatures with increasing milling time. The formation of a TiB2 phase by annealing indicates that the mechanochemical reaction of the Ni-Ti-B alloy does not comply with the alloy composition in the ternary phase diagram, and Ti-B bonds are found to be more preferable than Ni-B bonds.

Citations

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• Solid‐State Synthesis and Characterization of the Stable Nanostructured Ni21Ti2B6 Phase
  Tuncay Simsek, Baris Avar, Sadan Ozcan, Arun K. Chattopadhyay, Bora Kalkan
  physica status solidi (b).2021;[Epub]     CrossRef
• Synthesis and analysis of nanocrystalline β1-Cu3Al and β2-NiAl intermetallic-reinforced aluminum matrix composite by high energy ball milling
  Hong-Hai Nguyen, Minh-Thuyet Nguyen, Won Joo Kim, Jin-Chun Kim
  Metals and Materials International.2017; 23(1): 202.     CrossRef

In this study, ternary compound Max Phase Ti₂AlC material was mixed by 3D ball milling as a function of ball milling time. More than 99.5 wt% pure Ti₂AlC was synthesized by using spark plasma sintering method at 1000, 1100, 1200, and 1300°C for 60 min. The material characteristics of synthesized samples were examined with relative density, hardness, and electrical conductivity as a function of sintering temperature. The phase composition of bulk was identified by X-ray diffraction. On the basis of FE-SEM result, a terraced structures which consists of several laminated layers were observed. And Ti₂AlC bulk material obtained a vickers hardness of 5.1 GPa at the sintering temperature of 1100°C.

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Citations to this article as recorded by  

• Synthesis and reaction path of Ti‐Al‐C MAX phases by reaction with Ti‐Al intermetallic compounds and TiC
  Hojun Lee, Si Yeon Kim, Young‐In Lee, Jongmin Byun
  Journal of the American Ceramic Society.2023; 106(12): 7230.     CrossRef

In this study, nano-scale copper powders were reduction treated in a hydrogen atmosphere at the relatively high temperature of 350°C in order to eliminate surface oxide layers, which are the main obstacles for fabricating a nano/ultrafine grained bulk parts from the nano-scale powders. The changes in composition and microstructure before and after the hydrogen reduction treatment were evaluated by analyzing X-ray diffraction (XRD) line profile patterns using the convolutional multiple whole profile (CMWP) procedure. In order to confirm the result from the XRD line profile analysis, transmitted electron microscope observations were performed on the specimen of the hydrogen reduction treated powders fabricated using a focused ion beam process. A quasi-statically compacted specimen from the nanoscale powders was produced and Vickers micro-hardness was measured to verify the potential of the powders as the basis for a bulk nano/ultrafine grained material. Although the bonding between particles and the growth in size of the particles occurred, crystallites retained their nano-scale size evaluated using the XRD results. The hardness results demonstrate the usefulness of the powders for a nano/ultrafine grained material, once a good consolidation of powders is achieved.