In situ X-ray diffraction study of the phase transformation in the non-stoichiometric intermetallic compound Ti3Sn

• A new orthorhombic phase of the intermetallic compound Ti3Sn was found.
• A reversible orthorhombic-to-hexagonal transition into Ti3Sn was observed using XRD.
• The unit cell and space group of orthorhombic phase are defined.
• Crystallographic relations between orthorhombic and hexagonal phases are analyzed.

Phase transformations of Ti75.5Sn24.5 were investigated using in situ X-ray diffraction during heating. The as cast Ti75.5Sn24.5 was found to consist mainly of an orthorhombic Cmcm phase at room temperature; upon heating to 473 K the material undergoes a reversible group-subgroup transition to hexagonal P63/mmc (D019) phase. Crystal structure and lattice parameters of the orthorhombic phase are suggested based on X-ray and electron diffraction results. The crystallographic relation between parent and product phase is also discussed.