|Title:||Martensitic transformation and pseudoelasticity of aged Ti50.1Ni49.7Si0.2 shape memory ribbon||Authors:||Chen, C.-H.
|Keywords:||Nanoindentation; Shape memory alloys; Rapid solidification; Age hardening; Martensitic transformation; Superelasticity||Issue Date:||2014||Publisher:||ELSEVIER SCIENCE SA||Journal Volume:||593||Start page/Pages:||85||Source:||Materials Science and Engineering A||Abstract:||
The effect of aging on transformation sequence, microstructure evolution, hardness change and pseudoelasticity (PE) of Ti50.1Ni49.7Si0.2 ribbon is investigated. Ti50.1Ni49.7Si0.2 ribbon aged at 500°C for ≧1h undergoes a two-stage B2→R→B19' transformation during cooling. The microstructure and hardness of the aged ribbon are closely related to its composition. The matrix of the aged ribbon becomes Ni-rich because of its high Si content and low Ti/Ni ratio. A very high density Ti3Ni4 precipitate is observed in Ti50.1Ni49.7Si0.2 ribbons aged at 500°C for ≧1h, which gives the aged ribbons high hardness. Nanoindentation tests indicate that Ti50.1Ni49.7Si0.2 ribbon aged at 500°C for 15min has a maximal hardness of 5.5GPa and that aged for 336h decreases to 4.0GPa. The PE recovery of the ribbon is improved from 55% to 75% under a 100mN loading after aging at 500°C for 15min. The experimental results show that adjusting the composition of TiNi ribbon can effectively modify the microstructure, increase the hardness and the ribbon still retains excellent PE recovery. © 2013 Elsevier B.V.
|Appears in Collections:||機械工程學系|
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