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How do the crystal structures of iron and titanium change with temperature?

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electron hole: movement — materials science Movement of an electron hole in a crystal lattice.

In materials science, both iron and titanium are allotropic, meaning they undergo structural changes in their crystal lattice as temperature varies.123

Titanium

Pure titanium exists in two primary phases:
* Alpha ( $α$ ) phase: Below 883 °C (1,621 °F), titanium has a hexagonal close-packed (hcp) structure.45
* Beta ( $β$ ) phase: Above 883 °C, it transforms into a body-centred cubic (bcc) structure.45

Iron

Iron exhibits more complex allotropic behavior across its temperature range:
* Alpha-ferrite ( $α$ ): At room temperature, iron has a bcc structure.23
* Austenite ( $γ$ ): Upon heating to 912 °C (1,674 °F), the structure transforms into a face-centred cubic (fcc) arrangement.23
* Delta-ferrite ( $δ$ ): With further heating to 1,394 °C (2,541 °F), the bcc structure reappears and persists until the melting point of 1,538 °C (2,800 °F).23

These phase transformations are fundamental to heat treating processes, as they allow for the manipulation of mechanical properties by controlling the resulting microstructure.1