Abstract: The utilization of porous biomedical implants featuring a bimodal microstructure has garnered substantial interest within the scientific community. This study delves into the intricate interplay between processing parameters, microstructural attributes, and the tribo-mechanical performance of titanium grade 4, showcasing its potential to serve as implants to address compromised cortical bone tissue. The investigation meticulously examines the impact of milling duration (10 and 20 h), proportion of milled powder (50 and 75 wt%), and the volume fraction of space-holding agents (40-60 vol% NaCl) on the resulting characteristics of the bimodal microstructure, which plays a crucial role in achieving optimal biomechanical equilibrium. The Vickers microhardness, conventional and instrumented (P-h curves), and the wear behavior (ball-on disk) are discussed in terms of bimodal microstructure distribution, particle size and porosity level inherent to the fabrication conditions (mechanical milling + space-holder + hot-pressing). In general terms, milling time and milled powder fraction were the most influent parameters on the final properties of the materials. With the processing route used, the achieved microhardness values and wear behavior are comparable with those obtained by means of surface modifications or alloys. The Young's moduli obtained were in the range of 30-50 GPa, which could help to reduce the shielding phenomenon, while presenting a good mechanical resistance and wear behavior. In light of these findings, the fabricated specimen, composed of 75 wt% milled powder subjected to a 10-h milling duration, supplemented by a 60 vol% fraction of NaCl, emerges as a prime candidate manifesting superior biomechanical equilibrium. This judicious configuration exhibits a promising trajectory for its application in bone replacement endeavors.

Abstract: The aim of this work was to study the synthesis and electrochemical properties of Ti 2 wt %-Si alloys prepared by mechanical alloying (MA) and heat treatment. The MA process was performed under Ar atmosphere. The structural, morphological, and compositional evolutions during the milling and subsequent heat treatment were investigated by X-ray diffraction, energy-dispersive spectroscopy, and scanning electron microscopy. The electrochemical behavior was evaluated by open circuit potential and linear sweep voltammetry measurements. The results showed that the MA process promotes the formation of a supersaturated alpha-Ti-Si solid solution. During heat treatment, the Si remaining in the mechanically alloyed powders and the Si from the alpha-Ti-Si supersaturated solid solution reacted with Ti to form Ti-Si intermetallic compounds. These compounds have a fine and homogeneous distribution in the alpha-Ti matrix, which cannot be achieved by conventional casting methods. Additionally, the electrochemical evaluations revealed that the mechanically alloyed and heat-treated Ti 2 wt %-Si powders have better corrosion resistance in 1.63 M H2SO4 than the pure Ti and MA Ti-Si samples. This is likely due to the particular microstructure produced during the milling and subsequent heat treatment.

Abstract: La0.8Sr0.2MnO3 (LSM) perovskite as oxygen electrode material for the reversible solid oxide fuel cells (ReSOFC) was synthesized by the fast solution combustion method and assessed for subsequent calcination influence. The microstructural, morphological, compositional and optical properties of the obtained material were analyzed with X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM) coupled with an energy-dispersive X-ray spectroscopy detector (EDS) and UV-visible spectroscopy techniques. The XRD results showed the coexistence of rhombohedral R-3c and Pm-3m polymorphs for the perovskite phase, with a decreased fraction of the cubic phase as the temperature and/or time used for the calcination were increased. The HR-TEM images confirmed the existence of the R-3c and Pm-3m polymorphs for the sample subjected to calcination at 1300 degrees C, showing that the rapid combustion method did not allow the pure formation of the La0.8Sr0.2MnO3 phase for the calcination temperatures below 1400 degrees C, due to the swiftness of the combustion synthesis 500 degrees C for 5 min. The average grain size was found to be increased with the calcination time. The EDS analysis depicted a better agreement in stoichiometry with the theoretical composition. The apparent porosity was decreased with the increase in the temperature and calcination time due to the coalescence of the sintering pores. The sample obtained after the calcination at 1400 degrees C for 8 h exhibited 1.6% of porosity. The hardness was improved with the higher calcination time and temperature and reached a maximum value of 5.7 GPa that merely matched the bulk density. A similar trend was observed in the temperature dependence resistivity studies and all the samples presented a low resistivity of similar to 1.2 Omega cm in the temperature range of 600-700 degrees C. The optical characterization exhibited a broad absorption in 560-660 nm.