Vickers microhardness and indentation creep studies for erbium-doped ZnO nanoparticles

Abstract

The effect of erbium (Er) doping on the structural, magnetic and mechanical properties of Zn 1−x Er x O, with 0.00 ≤ x ≤ 0.10, samples was studied using X-ray powder diffraction, M-H magnetic hysteresis and digital Vickers microhardness tester, respectively. The samples were prepared by wet chemical co-precipitation method. Vickers microhardness (H v) measurements were carried out at different applied loads (0.25-10 N) and dwell times (t = 10-60 s) to study the mechanical performance of the samples. Experimental results of H v were analyzed using Meyer's law, and modeled according to Hays-Kendall, elastic/plastic deformation, modified proportional specimen resistance (MPSR) and Indentation Induced Cracking models. It was observed that the MPSR model was the most appropriate model for describing the load independent microhardness data of Er-doped ZnO nanoparticle samples. Indentation creep behavior of Zn 1−x Er x O samples was studied at room temperature by measuring the variation of H v with the dwell times (t = 10-60 s) at fixed applied loads F = 1, 5 and 10 N, respectively. The results showed that Er-doped ZnO nanoparticles samples possessed grain boundary sliding and dislocation climbs at low loads followed by dislocation creep for higher loads within the operative creep mechanism.

Application of the Composite Hardness Models in the Analysis of Mechanical Characteristics of Electrolytically Deposited Copper Coatings: The Effect of the Type of Substrate

“…The decrease in the composite hardness when increasing the dwell time is clearly observed for all thicknesses of the coatings and for both the applied loads. The main parameter defining the creep resistance characteristics of the coatings is a stress exponent, μ, and this parameter can be determined by the application of the Sar-gentAshby model [47,48]. According to this model, the dependence of Hc on t can be presented by Equation ( 6):…”

“…In Equation ( 6), ε0 is the strain rate at reference stress σ0, c is constant, t (in s) is dwell time and μ is the stress exponent. The values of the stress exponent around one indicate that the dominant mechanism affecting deformation is diffusion creep; for a value close to 2 it is a grain boundary sliding, and for μ values between 3 and 10 the dominant mechanism is dislocation creep and dislocation climb [48]. The main parameter defining the creep resistance characteristics of the coatings is a stress exponent, µ, and this parameter can be determined by the application of the Sargent-Ashby model [47,48].…”

“…In Equation ( 6), ε 0 is the strain rate at reference stress σ 0 , c is constant, t (in s) is dwell time and µ is the stress exponent. The values of the stress exponent around one indicate that the dominant mechanism affecting deformation is diffusion creep; for a value close to 2 it is a grain boundary sliding, and for µ values between 3 and 10 the dominant mechanism is dislocation creep and dislocation climb [48].…”

The investigation of mechanical and dielectric properties of Samarium doped ZnO nanoparticles

“…Recently, researches regarding the mechanical properties of nanoparticles showed a great interest as a result of the difference in the mechanical properties between nanoparticles and microparticles together with bulk materials allowing for many applications in variety of domains like tribology, surface engineering and nanomanufacturing/nanofabrication [23]. Mechanical parameters like hardness, yield strength, elastic modulus, fracture toughness and brittleness alter exceedingly with different doping [20] and their investigation for ZnO compound is vital because of its use in nano-electro-mechanical systems, transparent high power electronics and nano-generators [24]. In industry, hardness tests are often accustomed to find out the fabrication quality of the materials and especially the management of the effectiveness of heat treatment because of the simple nondestructive test applied rapidly.…”

Mechanical properties of biomass-derived silica nanoparticles reinforced PMMA composite material

“…The exponent in metallic materials signifies the creep mechanism. The value of exponent around 1 means that diffusion creep was the dominant creep mechanism, if the value of μ ≈ 2 the creep mechanism is a grain boundary sliding, and if the value of μ is in the range between 3-10, mechanism of indentation deformation will be dislocation climbs and dislocation creep [36,37]. In composite materials, the mechanism of viscoelastic behavior can be explained differently.…”