The anisotropy of the thermal expansion of α-titanium

In order to resolve the discrepancy found in earlier work, the anisotropic thermal expansion of α-titanium has been determined by the X-ray method. If a small range of temperature is used the coefficient of expansion observed along the hexagonal axis (α_c) is smaller than that in the basal plane (α_a). The nature of the deviation of the α-titanium structure from ideal hexagonal close-packing and the room temperature elastic behaviour of the metal have been shown to be in agreement with the result that α_c (5.6 × 10⁻⁶. °C⁻¹) is smaller than α_a (9.5 × 10⁻⁶. °C⁻¹).