Effects of growth rate and composition on the microstructure of directionally solidified NiMnGa alloys

Jian Chen; Michael A. Gharghouri; Calvin V. Hyatt

doi:10.1117/12.484695

13 August 2003 Effects of growth rate and composition on the microstructure of directionally solidified NiMnGa alloys

Jian Chen, Michael A. Gharghouri, Calvin V. Hyatt

Proceedings Volume 5053, Smart Structures and Materials 2003: Active Materials: Behavior and Mechanics; (2003) https://doi.org/10.1117/12.484695
Event: Smart Structures and Materials, 2003, San Diego, California, United States

Abstract

Magnetic shape memory (MSM) alloys give recoverable strain when subjected to an applied magnetic field. The strongest MSM effect has been observed in single crystals. The magnitude of the effect and the consistency of behavior over the entire volume of a sample is strongly dependent on the solute and phase distributions in crystals. Samples of stoichiometric and off-stoichiometric Ni2MnGa magnetic shape memory alloys were directionally solidified by a seedless Bridgman method using different rates of growth. The growth conditions used resulted in oriented polycrystals exhibiting a coarse cellular structure. Significant macro-segregation was observed, with the top of the ingot enriched in Mn and the bottom enriched in Ga. Micro-segregation also occurred, resulting in Mn-rich intercellular eutectic or eutectoid structures, and coarse intra- and inter-cellular Mn-rich particles. An increase in the pulling rate during the directional solidification process resulted in finer cellular and eutectic / eutectoid structures, as well as finer particles.

Citation Download Citation

Jian Chen, Michael A. Gharghouri, and Calvin V. Hyatt "Effects of growth rate and composition on the microstructure of directionally solidified NiMnGa alloys", Proc. SPIE 5053, Smart Structures and Materials 2003: Active Materials: Behavior and Mechanics, (13 August 2003); https://doi.org/10.1117/12.484695

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available