Improvement of compressive strength and ductility in NiAl based eutectic alloy by uniform high magnetic field treatment Hu-Tian Li a, * , Qiang Wang a, * , Kai Wang a , Ji-Cheng He a , Jian-Ting Guo b , Heng-Qiang Ye b a Key Laboratory of Electromagnetic Processing of Materials, Ministry of Education, Northeastern University, Shenyang 110004, China b Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China article info Article history: Received 12 June 2008 Accepted 31 July 2008 Available online 8 October 2010 Keywords: A. Nickel aluminides, based on NiAl B. Mechanical properties at ambient temperature B. Diffusion C. Heat treatment abstract With the development of superconducting technology, high magnetic fields (HMF) provide unique opportunity for materials and physics scientists to extend or exploit high performance of existing materials. In this paper, we report our findings of the improvement of compressive strength and ductility in a NiAl based eutectic alloy induced by high uniform magnetic field treatment. It shows that the compressive strength and ductility of NiAleCr(Mo)e(Ti,Hf) eutectic alloy were improved by 100 MPa and 12% respectively after 11T uniform magnetic field treatment. Microstructural characterization and frac- tography observation suggested that the modification of morphology and dispersed distribution of constituent phases through atomic diffusion induced by the HMF treatment could be responsible for the improvement of mechanical performance. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction As a B2 crystalline structural intermetallic compound (a bcc superlattice structure), NiAl has received more attention as a potential high temperature structural material for aerospace applications because it possesses the low density, high melting point and superior resistance to oxidation [1e4]. But its intrinsic brittleness and poor tolerance to damage at room temperature and low creep strength at elevated temperature heavily retard its usefulness to actual application. To resolve these problems, many investigations have been undertaken and as far as we know, the high temperature strength of NiAl-based alloys has been improved to nearly the same as the superalloys being used industrially [3e6]. So the demand for improving its room temperature ductility and toughness has become increasingly stronger. In our resent study, combined additions of Ti and Hf to NiAleCr(Mo) eutectic alloy on the Heusler precipitation behavior and compression deformation have been reported [7e9], demonstrating the favorable effects of TieHf co-additions due to the formation of b-Ti(M, M ¼ Hf,Cr,Ni) solid solution phase. Recently, the research of high magnetic fields (HMFs) has extended to almost all the material science fields with the development of superconducting magnet technology. Now, the application of HMF is expected as one of promising technologies in material processing [10e15]. In this report, the effect of high magnetic treatment on the microstructure and compression deformation behavior of a NiAleCr(Mo)e(Ti,Hf) near eutectic alloy are investigated detailedly. 2. Experimental procedure The nominal composition of NiAleCr(Mo)e(Ti,Hf) near eutectic alloy investigated is Ni33-Al29-Cr28-Mo6-Hf0.5-Ti3.5. The experi- mental alloy was manufactured by arc melting of pure Al, Ni, Cr, Mo, Ti and Hf element in argon atmosphere with a titanium oxygen- getter on a water-cooled copper hearth with a nonconsumable tungsten electrode. The detailed information on alloy design and preparation can be found in previous publications [4e6]. The HMF setup is schematically illustrated in Fig. 1 . It consists of a super- conducting magnet and a vacuum resistance furnace. The super- conducting magnet can produce an axial static magnetic field with a maximum magnetic flux density of 12 T at the position of B max where the magnetic field is uniform. The resistance furnace with inner diameter 33 mm is installed in the bore of the magnet and an R-type thermocouple at the center of the furnace is used to measure the furnace’s temperature. The specimens were put into corundum crucible of inner diameter 10 mm and length 50 mm and then placed at the position B max of magnetic field. The magnetic parameters used in the experiments are as follows. The specimen was heated to 1023 K at a heating rate of 5 K min À1 , and held at * Corresponding authors. E-mail addresses: john.li2009@gmail.com (H.-T. Li), wangq@epm.neu.edu.cn (Q. Wang). Contents lists available at ScienceDirect Intermetallics journal homepage: www.elsevier.com/locate/intermet 0966-9795/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.intermet.2010.08.018 Intermetallics 19 (2011) 187e190