Microstructure and Materials Properties of Understoichiometric TiBx Thin Films Grown by HiPIMS

In the present research article we report synthesis of TiB_x, 1.43n-situ mass- and energy-spectroscopy is used to explain the obtained compositional range. Excess B in overstoichiometric TiB_x thin films from DCMS results in a hardness up to 37.7±0.8 GPa, attributed to the formation of an amorphous B-rich tissue phase separating stoichiometric TiB₂ columnar structures. With a particular focus on characterization of the understoichiometric samples, we show that understoichiometric TiB_1.43 thin films synthesized by HiPIMS exhibit a superior hardness of 43.9±0.9 GPa, where the deficiency of B is found to be accommodated by Ti planar defects. The apparent fracture toughness, electrical resistivity and thermal conductivity of the same sample is 4.2±0.1 MPa√m, 367±7 μΩ·cm and 5.1 W/(m.K), respectively, as compared to corresponding values for overstoichiometric TiB_2.20 DCMS thin film samples of 3.2±0.1 MPa√m, 309±4 μΩ·cm and 3.0 W/(m.K).