The Effect of Grain Constraint, Heat Treatment and Compositional Change on the Behavior of Martensitic Transformations in Alloys with the Composition Near Cu-13Al-4Ni-1Zn (Mass%)

¹ Kokan Keisoku Co. Ltd., Minamiwatarida 1-1, Kawasaki-ward, Kawasaki 210, Japan
² Teikyo University, School of Science and Engineering, Toyosatodai 1-1, Utsunomiya 320, Japan
³ Benkan Co. Ltd., Rokusengoku Higashiura 5, Yabuzukahoncho, Nittagun, Gunma 379-23, Japan

Abstract

Martensitic transformation temperatures and the phase stability of martensites have been found to be influenced not only by alloy compositions and heat treatments but also by constraint effect against shape change associated with martensitic transforations, as a result of DSC measurements perfomed on single crystals and polycrystals of a CU-13.4Al -4.ONi-1.1Zn (mass%) alloy. The single crystals and polycrystals have been subjected to solution heat treatments (SHT) with being sealed into evacuated quartz tubes and without being sealed under dynamic vacuum, and followed by ice water quench, air cool and furnace cool. These specimens have shown different transformation behavior, which is a consequence of being under different conditions as follows. The first is compositional alterations expected to occur during the fabrication of the sigle crystal or during the SHT under the dynamic vacuum, the second is quenching rate which also depends on whether the SHT has been performed In the sealed or unsealed states, and the third is grain constraint effect which depends on whether single crystal or polycrystal. The origin of the observed different transformation behavior will be discussed.