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Effect of zirconium doping on the mechanical properties of W1−x Zr x B2 on the basis of first‑principles calculations and magnetron sputtered films

Maździarz Marcin, Psiuk Rafał, Krawczyńska Agnieszka, Lewandowska Malgorzata, Mościcki Tomasz

Archives of Civil and Mechanical Engineering

2022

Vol. 22, no. 4

art. no. e193, 2022

Potentially superhard polymorphs, hP6-P6/mmc-WB and hP3-P6/mmm-WB, were thoroughly analyzed with zirconium doping in the range of x=0-25%, within the framework of the first-principles density functional theory, from both a structural and a mechanical point of view. The obtained results were subsequently compared with the properties of material deposited by the magnetron sputtering method. All predicted structures are mechanically and thermodynamically stable. Theoretical calculations suggest a decrease in hardness and fracture toughness of the hP6 phase with zirconium doping but no such effect on the hP3 phase. It was observed that an additional defect in the analyzed structure significantly weakens the hP6 phase but strengthens the hP3 phase. The deposited films are characterized by greater hardness but lower fracture toughness. The results of experiments show that not only is solid solution hardening responsible for strengthening the predicted new material but also the change in microstructure, the Hall–Petch effect and vacancies.

A multiscale experimental analysis of mechanical properties and deformation behavior of sintered copper-silicon carbide composites enhanced by high-pressure torsion

Nosewicz Szymon, Bazarnik Piotr, Clozel Melanie, Kurpaska Łukasz, Jenczyk Piotr, Jarząbek Dariusz, Chmielewski Marcin, Romelczyk-Baishya Barbara, Lewandowska Malgorzata, Pakieła Zbigniew, Huang Yi, Langdon Terence G.

Archives of Civil and Mechanical Engineering

2021

Vol. 21, no. 3

776--794

Experiments were conducted to investigate, within the framework of a multiscale approach, the mechanical enhancement, deformation and damage behavior of copper–silicon carbide composites (Cu–SiC) fabricated by spark plasma sintering (SPS) and the combination of SPS with high-pressure torsion (HPT). The mechanical properties of the metal–matrix composites were determined at three different length scales corresponding to the macroscopic, micro- and nanoscale. Small punch testing was employed to evaluate the strength of composites at the macroscopic scale. Detailed analysis of microstructure evolution related to SPS and HPT, sample deformation and failure of fractured specimens was conducted using scanning and transmission electron microscopy. A microstructural study revealed changes in the damage behavior for samples processed by HPT and an explanation for this behavior was provided by mechanical testing performed at the micro- and nanoscale. The strength of copper samples and the metal–ceramic interface was determined by microtensile testing and the hardness of each composite component, corresponding to the metal matrix, metal–ceramic interface, and ceramic reinforcement, was measured using nano-indentation. The results confirm the advantageous effect of large plastic deformation on the mechanical properties of Cu–SiC composites and demonstrate the impact on these separate components on the deformation and damage type.