a Fundamental Physics Center, University of Science and Technology of China, Hefei 230026, China; b Department of Physics, University of Science and Technology of China, Hefei 230026, China; c Institute of Solid State Physics, Academia Sinica, Hefei 230031, China
Abstract The thermal diffusivities of nanostructured NiAl (n-NiAl) alloys wit h different relative densities and the polycrystalline NiAl alloy are measured by using photoacoustic technique in which the signal is detected at the front surface while the rear-surface is excited. It is shown that the values of thermal diffusivity of the nanostructured NiAl alloy are lower than that of the polycry stalline NiAl alloy. The thermal diffusivities of n-NiAl alloys decrease with t he decrease of their relative densities when they are over 70%. When the relativ e density of n-NiAl alloys is lower than 70%, an anomalous increase of thermal diffusivity is observed, which indicates there exists a critical excess volume ΔVc (or critical relative density) in n-NiAl alloys near 70%. Th e results are discussed.
Received: 04 March 1997
Revised: 17 January 1998
Accepted manuscript online:
Fund: Project supported in part by the Special Research Foundation for Ph. D. Station(No. 020903) and National Laboratory of Modern Acoustics, Nanjing, China.
Cite this article:
DU YING-LEI (杜英磊), WU BAI-MEI (吴柏枚), QIN XIAO-YING (秦晓英), ZHANG LI-DE (张立德) THE THERMAL DIFFUSIVITIES OF NANOSTRUCTURED NiAl ALLOYS MEASURED BY USING PHOTOACOUSTIC TECHNIQUE 1998 Acta Physica Sinica (Overseas Edition) 7 451
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