Surface analysis of the stress-induced, impurity driven face centered cubic titanium phase and the ranging lattice parameter sizes

• Published in: Materials today communications 2020-09, Vol.24, p.101168, Article 101168
• Main Authors: Tshwane, D.M, Modiba, R., Bolokang, A.S
• Format: Article
• Language: English
• Subjects: FCC phase; Lattice parameter; Stress-induced; TiHx; TiOx
• ISSN: 2352-4928; 2352-4928
• DOI: 10.1016/j.mtcomm.2020.101168

[Display omitted] •FCC Ti, TiHx, TiH2, TiOx and TiO2 were investigated by the first principle calculations.•FCC phase in pure Ti with a lattice parameter of a = 4.11 Å•TiHx (a = 4.19 Å) and TiOx (a = 4.08 Å) lattice parameters were calculated.•FCC Ti with a = 4.140 Å for 0.32 mm deformed plates was detected.•The FCC Ti phase is both impurity as well as stress-induced driven. The first-principle calculations were used to compare the elastic properties and lattice parameters of the face-centered cubic (FCC) commercially pure (CP) titanium (Ti), titanium hydrides as well as titanium oxide structures. It was found that the lattice parameter of the FCC Ti phase is a = 4.11 Å in agreement with literature. Moreover, lattice parameters of the FCC TiHx, TiH2, TiOx and TiO2 are a = 4.19 Å, a = 4.42 Å, a = 4.08 Å and a = 4.89 Å, respectively. The calculated formation energy demonstrated that FCC TiOx phase is energetically favourable than the FCC TiHx structure. Partial density of states (PDOS) for FCC TiOx and TiHx structures revealed a significant difference and confirmed the stability formation of TiOx and TiHx phases. Moreover, mechanical properties of the FCC TiOx and TiHx structures exposed that only TiHx phase is unstable at 0 K. Deformation by repeatedly applying impact loading at room temperature of the 4 mm Ti plate was manually achieved. The two deformed plates had a final thickness of 1.26 mm and 0.32 mm, respectively. X-ray diffraction (XRD) analysis revealed a hexagonal close packed to face centered cubic phase transformation. Moreover, an FCC phase with lattice parameter a = 5.743 Å was detected on the 1.26 mm while the 0.32 mm sample was composed of a = 4.140 Å. The latter phase had a lattice parameter comparable to the predicted value of a = 4.11 Å.