کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1446440 | 1509615 | 2012 | 9 صفحه PDF | دانلود رایگان |
Direct measurements of reversible magnetic-field-induced strain (MFIS) on a single crystalline Ni45Co5Mn36.5In13.5 metamagnetic shape memory alloy were attained via magnetic-field-induced martensitic transformation under different stress levels and at various temperatures. This was achieved using a custom-designed micro-magneto-thermo-mechanical testing system capable of applying constant stress while measuring strain and magnetization simultaneously on the samples, which can fit into conventional superconducting magnets. MFIS levels are reported as a function of temperature, magnetic field and external bias stress. It was necessary to apply an external bias stress in these materials to detect a notable MFIS because a magnetic field does not favor a specific martensite variant resulting in no shape change even though magnetic field leads to reversible martensitic transformation. Fully recoverable transformation strains up to 3.10% were detected under repeated field applications in the presence of different compressive stress levels up to 125 MPa. The bias stress opposes the field-induced martensite-to-austenite phase transformation and causes the critical field for the transformation to increase at a given temperature in accordance with the Clausius Clapeyron relationship. The effect of the bias stress on the kinetic arrest of austenite is also explored.
Journal: Acta Materialia - Volume 60, Issue 20, December 2012, Pages 6883–6891