High damping performances over wide temperature range in the B doped Ti-Ni shape memory alloys

Abstract

• The Ti-Ni alloys with B addition undergo B2 ↔ B19′ martensitic transformation. • Two high internal friction peaks are observed in the B doped Ti-Ni alloys. • One internal friction is derived from reversible martensitic transformation. • The other originates from the interactions between boron and twinning boundaries. In present work, the microstructure, martensitic transformation behavior and damping properties of the B doped Ti-Ni shape memory alloys were investigated. The B2 parent phase and B19′ martensite phase are both detected in the whole samples, irrespective of B contents. In addition, the TiB whiskers are observed in the alloy with high boron contents. The martensitic transformation temperatures increase firstly and then decreases with the increasing of the B contents. The Ti-Ni alloys with B addition exhibit two high internal friction peaks, which are derived from the B2 ↔ B19′ martensitic transformation and interactions between boron and twinning boundaries, respectively. The tanδ of low temperature relaxation peak can be up to approximately 0.074 in the alloy with 0.7 at.% B contents. The introduction of proper interstitial atoms is considered as promising method to improve the damping performances.