High-cycle fatigue of 10M Ni-Mn-Ga magnetic shape memory alloy in reversed mechanical loading

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  • AdaptaMat Ltd

Abstract

Application of Ni-Mn-Ga magnetic shape memory alloys in magnetic-field-induced actuation relies on their performance in long-term high-cycle fatigue. In this paper the performance and changes in the microstructure of a Ni-Mn-Ga 10M martensite single crystal material are reported in a long-term mechanically induced shape change cycling. The longest test was run for 2 × 109 cycles at a frequency of 250Hz and a strain amplitude of 1%. After the test a clear increase of the dynamic stiffness of the material was detected. Three specimens out of ten were cycled until fracture occurred and their fracture mechanism was studied. It was observed that the macroscopic crack growth took place roughly at a 45° angle with respect to the loading direction that was along the 〈100〉 crystallographic direction of the sample. The macroscopic fracture plane seemed to correspond roughly to the {111} crystal planes. On a microscopic scale the fracture propagated in a step-like manner at least partly along crystallographic planes. The steps at the fracture plane correspond to the {101} twin planes, with the height of steps along the 〈101〉 direction. The final fracture of the samples occurred in a brittle manner after the critical stress was exceeded.

Details

Original languageEnglish
Article number075014
Pages (from-to)1-10
Number of pages10
JournalSmart Materials and Structures
Volume19
Issue number7
Publication statusPublished - 1 Jun 2010
MoE publication typeA1 Journal article-refereed

ID: 4663710