Microstructure and elevated temperature mechanical behavior of cast NiAl–Cr(Mo) alloyed with Hf

• Published in: Journal of alloys and compounds Vol. 343; no. 1-2; pp. 142 - 150
• Main Authors: Guo, J.T, Cui, C.Y, Qi, Y.H, Ye, H.Q
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 16-09-2002; Elsevier
• Subjects: Applied sciences; Creep; Cross-disciplinary physics: materials science; rheology; Deformation; Elasticity. Plasticity; Exact sciences and technology; Hot isostatic press; Materials science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; NiAl–28Cr–5Mo–1Hf; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Solidification; Deformation; Creep; NiAl–28Cr–5Mo–1Hf; Hot isostatic press; High resolution; Hot isostatic pressing; Aluminium alloy; Experimental study; Compression test; Tension test; Multi-element alloys; Casting; Molybdenum alloy; Transmission electron microscopy; Hafnium alloy; Chromium alloy; Plasticity; Microstructure; True stress true strain curve; Power law; Nickel alloy
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/S0925-8388(02)00205-0

An NiAl–Cr(Mo) alloy modified with Hf was fabricated by vacuum induction, melted and drop cast and then was hot isostatically pressed (HIPed) at 1523 K, 200 MPa for 4.5 h. The alloy was mainly composed of NiAl matrix, Cr(Mo) and Hf-rich phase distributed on the NiAl and Cr(Mo) phase boundary. The NiAl–Cr(Mo) and NiAl–Ni2AlHf interfaces were also investigated. Its elevated temperature compressive behavior was studied and the deformation features of the alloy could be adequately described by standard power-law which is usually used to characterize creep behavior for various metallic materials. The stress exponent n as well as the activation energy Q was calculated by fitting the experimental data to the power-law and temperature-compensated power-law equation. The possible strengthening mechanism was also discussed. Because the alloy had relatively high tensile strength, the tensile creep was performed at 1373 K and, as concluded from the stress component of different testing methods, the creep behavior may not be influenced by the testing method.