Plasticity characteristic obtained by indentation

Abstract

A dimensionless parameter δH = εp/εt (where εp and εt are the average values of plastic and total deformation of material on the contact area indenter–specimen) may be used as the plasticity characteristic of materials, which made it possible to characterize the plasticity of materials that are brittle in standard mechanical tests. δH may be calculated from the values of microhardness HM, Young's modulus E and Poisson's ratio ν. In instrumented indentation the plasticity characteristic δA = Ap/At (Ap and At are the work of plastic and total deformation during indentation) may be calculated. δA ≈ δH for materials with δH > 0.5, i.e. for all metals and the majority of ceramic materials. In this case, the theoretical equation δA ≈ δH = 1–10.2 · (1 − ν − 2ν2)(HM/E) is satisfied in experiments with the Berkovich indenter. The influence of the temperature and structural parameters (dislocation density and grain size including nanostructured materials) on δH is discussed.

Nanostructured Ti‐Zr‐Pd‐Si‐(Nb) bulk metallic composites: Novel biocompatible materials with superior mechanical strength and elastic recovery

“…Hence, these materials would be more resistant to impact loading than Ti-40Nb. 46 With the aim to study the contribution of the individual phases or regions, to the overall mechanical response, nanoindentation tests applying a maximum load of 3 mN were carried out for Ti 45 Table IV. SEM images of representative indents on each region are presented in Figure 6 (a)-(d).…”

Mechanical properties of powder titanium at different production stages. I. Densification curves for titanium powder billets

“…To verify this assumption, we compared the yield stress of deformed compact material with the hardness of individual powder particles, H μ . According to the theory that associates yield stress with hardness, the relation H μ /3 = σ y applies well to deformed materials [24][25][26]. Table 4 indicate that the H μ /3 values for the central part of a powder particle are practically the same as σ y of the compact sample deformed to the same equivalent strain.…”

Structure and mechanical properties of iron after surface severe plastic deformation under friction with simultaneous nitrogen saturation: II. The mechanical properties of nano- and submicrocrystalline iron saturated with nitrogen during deformation

“…2). It is due to the fact that the hardness decreases more quickly than Young's modulus and that δ A is mainly determined by the H M /E ratio [26,29]. Essentially, the dispersion of bcc iron to the nanocrystalline state (d < 50 nm) is accompanied by an increase in the plasticity charac teristic, while the dispersion of the grain structure of fcc metals to 20 nm only decreases the plasticity [6].…”