Reduced functional degradation in conventional and magnetic shape memory alloys through optimized microstructures

• Applicant: Professor Dr.-Ing. Hans Jürgen Maier
• Subject Area: Materials Science
• Term: from 2008 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 64529786

• Final Report Year: 2010

Final Report Abstract

The presented results support the use of single crystals instead of polycrystals, as they allow the microstructure to be controlled without effects of boundary grains. It was shown that – due to the precipitation of disperse particles – aging is a promising approach to produce nanocomposites based on either NiTi or CoNiAl. Thus, alloys with reduced functional degradation and high-temperature superelasticity can be generated. It was also demonstrated that not only aging under compression, which results in the formation of precipitates perpendicular to the loading axis, leads to reduced functional degradation in NiTi single crystals, but also aging under tensile stresses.

Publications

• Design and Application of a Mechanical Load Frame for In-situ Investigation of Ferromagnetic Shape Memory Alloys by Magnetic Force Microscopy, Rev. Sci. Instruments, 79, 2008, 113701-1 - 113701-4
  D. Niklasch, H.J. Maier, I. Karaman
  
• Effect of Disperse Ti3Ni4 Particles on the Martensitic Transfomations in Titanium Nickelide Single Crystals , Phys. Met. Metallo., 106, 2008, 577-589
  E.Yu. Panchenko, Yu.I. Chumlyakov, I.V. Kireeva, A.V. Ovsyannikov, H. Sehitoglu, I. Karaman, H.J. Maier
  
• High-temperature superelasticity in CoNiGa, CoNiAl, NiFeGa and TiNi Monocrystals, Russian Physics Journal, 51, 2008, 1016-1036
  Yu.I. Chumlyakov, I.V. Kireeva, E.Yu. Panchenko, E.E. Timofeeva, Z.V. Pobendennaya, S.V. Chusov, I. Karaman, H.J. Maier, E. Cesari and V.A. Kirillov
  
• Orientation Dependence and Tension/Compression Asymmetry of Shape Memory Effect and Superelasticity in Ferromagnetic Co40Ni21Al27, Co49Ni21Ga30 Co and Ni54Fe19Ga27 Single Crystals, Mater. Sci. Eng. A, 481-482, 2008, 95-100
  Y. Chumlyakov, E. Panchenko, I. Kireeva, I. Karaman, H. Sehitoglu, H.J. Maier, A. Tverdokhlebova, A. Ovsyannikov
  
• Cyclic Deformation and Austenite Stabilization in Co35Ni35Al30 Single Crystalline High-temperature Shape Memory Alloys, Acta Mater., 57, 2009, 6123-6134
  J. Dadda, H.J. Maier, I. Karaman, Y.I. Chumlyakov
  
• High-Temperature Superelasticity and the Shape-Memory Effect in [001] Co-Ni-Al Single Crystals, Phys. Met. Metallo., 107, 2009, 194-205
  Yu.I. Chumlyakov, E. Yu. Panchenko, A. V. Ovsyannikov, S. A. Chusov, V. A. Kirillov, I. Karaman, H.J. Maier