Hybrid processing of TiC/TiCu/C composites with tailored hardness

This work reports the effect of TiC volume fractions on hardness of TiC/TiCu/C composites synthesized through in situ reactive infiltration of Ti-Cu alloy into porous carbon preforms prepared by 3 D-printing. Reactive melt infiltration of the alloy at 1100 °C under argon into C-preforms with different porosities resulted in materials composed of TiC, Cu-rich intermetallic matrix (Ti3Cu4) and residual carbon. The microstructure consists of TiC grains distributed along the Cu-Ti/C boundary. The hardness of TiC/Ti3Cu4/C composites could be tailored by the TiC volume fraction and the distribution in the composites, which are determined by the processing parameters and the initial porosity of the carbon templates in 3 D-printing stage. The hardness of the produced composites ranges from 350 HV to 570 HV and could be tailored by the TiC volume fraction and distribution in the composites, which are determined by the processing parameters and the initial porosity of the carbon-preforms.

Discrete Element Framework for Determination of Sintering and Postsintering Residual Stresses of Particle Reinforced Composites

In this paper, the discrete element method framework is employed to determine and analyze the stresses induced during and after the powder metallurgy process of particle-reinforced composite. Applied mechanical loading and the differences in the thermal expansion coefficients of metal/intermetallic matrix and ceramic reinforcing particles during cooling produce the complex state of stresses in and between the particles, leading to the occurrence of material defects, such as cracks, and in consequence the composite degradation. Therefore, the viscoelastic model of pressure-assisted sintering of a two-phase powder mixture is applied in order to study the stress field of particle assembly of intermetallic-ceramic composite NiAl/Al2O3. The stress evaluation is performed at two levels: macroscopic and microscopic. Macroscopic averaged stress is determined using the homogenization method using the representative volume element. Microscopic stresses are calculated both in the body of particles and in the contact interface (necks) between particles. Obtained results are in line with the cooling mechanism of the two-phase materials.

Ni–Sn intermetallics as an efficient buffering matrix of Si anodes in Li-ion batteries

High-capacity Si-based anodes with good coulombic efficiency and long-cycle life are achieved by embedding silicon nanoparticles in dual Ni3Sn4/Ni3Sn2 active/inactive intermetallic matrix.