Figure 2: Mechanical properties and Raman spectroscopy analysis.
From: Enhanced mechanical properties of nanocrystalline boron carbide by nanoporosity and interface phases
(a) Indentation force versus depth curves during loading and unloading with the maximum loads ranging from 200 to 1,000 mN at a constant loading rate of 7.06 mN s−1. (b) The variation of mean value of elastic modulus (E) and micro-indentation hardness (H) plots ranging from 290–200 GPa and 28–21 GPa at different loading forces (green colour). For comparison, the data taken from B4C single crystals (refs 4,21, E ranging from 400–450 GPa and H from 40–42 GPa) and microcrystalline B4C (refs 17,18,19,20, E ranging from 270–340 GPa and H from 25–32 GPa) are also plotted here. The data ranges marked by the dashed blue dotted lines correspond to single crystals B4C and the data ranges marked by the dashed red dotted lines correspond to microcrystalline B4C. (c) The variation of mean fracture toughness as a function of loading forces (green colour). For comparison, the data taken from microcrystalline B4C (refs 18,19,20,24,25, red dotted lines) are in the range from 2 to 2.8 MPa m1/2.The measured fracture toughness of n-B4C is ~3.6–4.7 MPa m1/2,much higher than that of microcrystalline B4C. The error bars represent the standard deviation from all the ten indentations measurements. (d) Raman spectra taken from the pristine area and residual indents of n-B4C at different loads.
