Training Effect on Microstructure and Shape Recovery in Ti-Pd-Zr Alloys

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Abstract

<p>The training effect of microstructure and shape recovery on Ti-50Pd-xZr (x = 7 and 10) at% and Ti-50Pd-xZr-(5-x)V (x = 1, 2.5, and 4) high-temperature shape memory alloys were investigated. Zr was selected as an alloying element as it is known to improve the shape recovery of TiPd. As a further alloying element, V was selected because it is effective in strengthening TiPd. The dependence of Zr content and V addition on the martensitic transformation (MT) temperature, shape recovery, and training effect were investigated. For example, <i>M</i><sub>f</sub>, decreased with increasing Zr from 480℃ in Ti-50Pd to 302℃ in Ti-50Pd-10Zr. In Ti-50Pd-xZr-(5-x)V, when the total amount of Zr and V was 5 at%, the MT temperatures did not change drastically. The MT temperatures ranged between 350 and 550℃.</p><p>Shape recovery was investigated using the thermal cyclic test under a constant applied stress in the range of 15 to 200 MPa. Perfect recovery was obtained at low stresses, while irrecoverable strain was observed at high stresses. For Ti-50Pd-2.5Zr-2.5V and Ti-50Pd-1Zr-4V, creep deformation was observed above 150 MPa. To obtain perfect recovery, training (repeated thermal cyclic tests under a constant applied stress) was performed. Perfect recovery was obtained for the alloys by training, except for Ti-50Pd-4Zr-1V. Ti-50Pd-10Zr achieved perfect recovery up to 200 MPa, while Ti-50Pd-1Zr-4V achieved perfect recovery up to 150 MPa. Other alloys achieved perfect recovery at lower stresses of 65 or 50 MPa. The microstructure changed from a random martensite variant to a specific orientation during training, to accommodate the large strain during deformation. It was found that a strong texture led to perfect shape recovery.</p>

Journal

  • MATERIALS TRANSACTIONS

    MATERIALS TRANSACTIONS 58(10), 1479-1486, 2017

    The Japan Institute of Metals and Materials

Codes

  • NII Article ID (NAID)
    130006096706
  • NII NACSIS-CAT ID (NCID)
    AA1151294X
  • Text Lang
    ENG
  • ISSN
    1345-9678
  • NDL Article ID
    028534862
  • NDL Call No.
    Z53-J286
  • Data Source
    NDL  J-STAGE 
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