日本金属学会誌

J. Japan Inst. Metals, Vol. 59, No. 8 (1995),
pp. 774-779

Effect of Quenching Rate on Martensitic Transformation Temperaturein Cu-Al-Ni Shape Memory Alloys

Masayoshi Nakaniwa, Koichi Sugimoto, Kiyoshi Kamei,Yasuhiko Nakamura and Takashi Sugimoto

Department of Materials Science and Engineering, Faculty of Engineering, Kansai University, Suita

Abstract:

Experiments were carried out for Cu-xAl-5Ni-2Mn-1Ti shape memory alloys (x=11.45, 11.77, 11.88 mass%) in order to examine the effect of quenching rate on the transformation temperatures (Ms, Mf, As and Af). The quenching rate was varried from 5 to 1{×}104 K/s by changing the temperature of quenching media.
The transformation temperatures were determined by DSC measurements for all the samples quenched and are plotted as a function of quenching rate.

It was found that all the transformation temperatures decreased by about 10 K, when the quenching rate was increased 10 times as large as its initial value. The reason was explained by considering the degree of order in the beta-phase. The primary α- and γ2-phases do not precipitate even during air-cooling on quenching in the alloys with 11.77 and 11.88%Al, being close to the eutectoid composition. Therefore, no remarkable change in martensitic transformation temperature with reducing quenching rate was observed in these alloys. In other words, it can be concluded that these alloys are suitable for heat treatments in practice, where the specimens are cooled more slowly.


(Received February 10, 1995)

Keywords:

shape memory alloy, copper-aluminium-nickel alloy, copper-aluminium-nickel-manganese-titanium alloy, martensite, martensitic transformation temperature, heat treatment, quenching rate, degree of order


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