In situ synthesized Ti5Si3/Ti–Mo lightweight structural composites

• In situ Ti5Si3/Ti–Mo lightweight composites were developed.
• Significant increase of strength was obtained.
• Ti5Si3 and Mo substitutional solution played different roles in strengthening mechanism.

Ti–Si and Ti–Mo alloys are considered to be potential high-temperature structural materials, thus it is interesting to develop new materials from Ti–Mo–Si ternary system by utilizing the strengthening mechanisms of both binary systems. In the present work, a series of composites in which Ti solid solution (partially substituted by Mo) matrix is reinforced by the eutectic cell Ti5Si3 + Ti have been in situ synthesized by using non-consumable vacuum arc melting. The composites exhibit the hypoeutectic microstructure consisting of primary α- or β-(Ti, Mo) solid solution and the fine eutectic cell. Besides the strengthening effect of Ti5Si3 compound, Mo element plays an important role in the composites through solid solution hardening, phase transformation hardening and fine grain hardening. All the above factors result in the significant improvement of mechanical properties, i.e. the yield strength increases from 768.54 MPa to 1450.62 MPa when Mo content changes from 0 to 10 at.%. Although some brittle characteristics can be found on the fractured surfaces of the Mo-added samples, relatively high plasticity is obtained in all the in situ Ti5Si3/Ti–Mo composites, which guarantees the application of these composites as structural materials.