Structural-functional integrated TiBw/Ti–V–Al lightweight shape memory alloy composites.

Driven by the increasing demands in advanced aerospace engineering, the integrated structural and functional materials are explored. In present study, we fabricate the TiB w /Ti–V–Al lightweight shape memory alloy composites with large recoverable strain (>5 %), high specific strength (>200 MPa cm3/g) and good elongation (>20 %). The satisfied structural and functional performances are attributed to the unique gradient microstructure, including TiB whiskers, short-range martensitic nanodomains and long-range martensitic microdomains. TiB w with the optimized orientation exhibits high load-bearing capacity. The transition area between TiB w and matrix is composed of short-range martensitic nanodomains. Nanodomains are affected by the diffused interstitial B atoms and local internal stress field regulated by TiB w. The elastic interaction energy between nanodomains and TiB w are calculated according to the Eshelby method. Upon deformation, nanodomains grow to long-range martensitic laths. The long-range martensitic laths keep stable after unloading. The microstructure evolution ties well with the Landau free energy model. It achieves effective loading transfer from matrix to reinforcement phase, resulting in less irreversible defects and better shape memory effect. In addition, grain refinement strengthening, loading transfer strengthening and solution strengthening are utilized to achieve the improvement of the strength and plasticity. The finding offers a promising inspiration for the development of new type shape memory alloy composites with integrated structural and functional properties. [ABSTRACT FROM AUTHOR]