Microstructural Evolution, Thermodynamics, and Kinetics of Mo-Tm2O3 Powder Mixtures during Ball Milling

Abstract

The microstructural evolution, thermodynamics, and kinetics of Mo (21 wt %) Tm2O3 powder mixtures during ball milling were investigated using X-ray diffraction and transmission electron microscopy. Ball milling induced Tm2O3 to be decomposed and then dissolved into Mo crystal. After 96 h of ball milling, Tm2O3 was dissolved completely and the supersaturated nanocrystalline solid solution of Mo (Tm, O) was obtained. The Mo lattice parameter increased with increasing ball-milling time, opposite for the Mo grain size. The size and lattice parameter of Mo grains was about 8 nm and 0.31564 nm after 96 h of ball milling, respectively. Ball milling induced the elements of Mo, Tm, and O to be distributed uniformly in the ball-milled particles. Based on the semi-experimental theory of Miedema, a thermodynamic model was developed to calculate the driving force of phase evolution. There was no chemical driving force to form a crystal solid solution of Tm atoms in Mo crystal or an amorphous phase because the Gibbs free energy for both processes was higher than zero. For Mo (21 wt %) Tm2O3, it was mechanical work, not the negative heat of mixing, which provided the driving force to form a supersaturated nanocrystalline Mo (Tm, O) solid solution.

Influence of Temperature, Pressure, and Humidity on the Stabilities and Transition Kinetics of the Various Polymorphs of FAPbI3

“…Yet, dry grinding or ball milling the starting FAI and PbI 2 powders may produce the perovskite phase ,, and similarly for MAPbI 3 (MAPI, MA = methylammonium [CH 3 NH 3 ] + ). Although a relationship between the application of high pressure and mechanosynthesis is not recognized, it can be estimated that in ball milling, the impacting balls generate pressures of several gigapascals in the contact region …”

“…Although a relationship between the application of high pressure and mechanosynthesis is not recognized, it can be estimated that in ball milling, the impacting balls generate pressures of several gigapascals in the contact region. 23 There are also reports of new phases, also with improved photovoltaic properties and stabilities, obtained after the application of high pressure. These phases generally have shorter bonds, higher orbital overlap, and reduced band gap, resulting in enhanced photocurrents.…”

Microstructural Evolution of Dy2O3-TiO2 Powder Mixtures during Ball Milling and Post-Milled Annealing

“…High-energy ball milling has been widely used to prepare various types of materials, such as supersaturated solid solutions, metastable crystalline materials [1], quasicrystal phases [2], nanostructured materials [3], and amorphous alloys [4]. The technology was initially used in place of blending and sintering at elevated temperatures to prepare ceramic-strengthened alloys [5,6].…”

Microstructure and Mechanical Properties of Ni-20Cr-Eu2O3 Composites Prepared by Vacuum Hot Pressing

“…During high-energy ball milling, Ni and Cr powder particles become finer since they are repeatedly flattened, cold-welded, and fractured [ 25 , 26 ]. Eu 2 O 3 is a brittle powder, and the long-term milling process can provide the driving force for the Eu 2 O 3 particle dissolution of Eu and O atoms into Ni/Cr crystal structure to form a supersaturated solid solution [ 27 , 28 ]. From Figure 2 and Figure 3 , when the contents of Eu 2 O 3 are 5 wt.% and 10 wt.%, they almost disappear on the surface of matrix, hence, Eu 2 O 3 was fined, nano-crystallized, amorphized, and then mechanically dissolved into the matrix during the 2 h mechanical alloying process.…”