2019 Volume 60 Issue 2 Pages 263-268
Solid solution strengthening effect by oxygen (O) and nitrogen (N) atoms of α-titanium (Ti) materials was quantitatively evaluated using Labusch model by consideration of the experimental data. When using Labusch model to predict solid solution strengthening improvement, an application of the isotropic strains by solute elements is generally assumed to estimate Fm value. It is, however, difficult to exactly calculate Fm value for α-Ti materials with O and N solute atoms because the anisotropic strains are induced in α-Ti crystal with hcp structure by these elements. In this study, Fm value was experimentally derived from the relationship between 0.2% yield stress and solute elements (O and N atoms) content of powder metallurgy Ti materials. As a result, the strengthening improvement was proportional to c2/3/Sf (c: soluted atom content, Sf: Schmid factor), and its factor of proportionality of Ti–O and Ti–N materials was 4.17 × 103 and 3.29 × 103, respectively. According to this analysis, it was clarified that Fm value of Ti–O and Ti–N materials was 6.22 × 10−10 and 5.21 × 10−10, respectively, and then the estimated strengthening improvement by using these values was significantly agreed with the experimental results of PM Ti materials with O and N solution atoms.
This Paper was Originally Published in Japanese in J. Jpn. Soc. Powder Powder Metallurgy 65 (2018) 407–413.