Detection of shock-wave-induced internal stresses in Cu-Al-Ni shape memory alloy by means of acoustic technique

• Published in: Scripta materialia Vol. 43; no. 12; pp. 1051 - 1057
• Main Authors: Emel’yanov, Yu, Golyandin, S, Kustov, S, Nikanorov, S, Pugachev, G, Sapozhnikov, K, Sinani, A, Van Humbeeck, J, Schaller, R, De Batist, R
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 27.11.2000
• Subjects: Copper alloy; Elastic properties; Impact shock-wave loading; Internal friction; Martensitic transformation; Impact shock-wave loading; Martensitic transformation; Internal friction; Elastic properties; Copper alloy
• ISSN: 1359-6462; 1872-8456
• DOI: 10.1016/S1359-6462(00)00538-8

The present results indicate that the stress-induced beta sub 1 - > gamma sub 1 exp ' martensitic occurs for an impact duration of 2x10 exp -6 s. This time interval appears to be sufficient also for the subsequent deformation of the gamma sub 1 exp ' martensitic phase to occur. A structure memory effect has been found: Cu-Al-Ni austenitic crystals, shock-loaded at room temperature to induce gamma sub 1 exp ' -martensite, recall during subsequent temperature-induced martensitic transformation the martensitic variant structure (elastic properties) formed under the shock loading. Elastic properties of quenched beta sub 1 exp ' and gamma sub 1 exp ' crystals of the Cu-Al-Ni systems are extermely sensitive to the shock-wave loading. Mechanisms of these effects, and of the structure memory effect, include the generation of internal stresses due to the high internal stresses by impact loading of the beta sub 1 exp ' martensitic phase is also detected by several anelastic phenomena. In contrast to elastic and anelastic properties, transformation temperatures are insensitive to the impact loading, pointing to the difference of structural elements responsible for the anelastic effects and for the interval and hysteresis of the thermoelastic martensitic transformation. Crystals of two compositions, Cu-13.2 wt.% Al-4.0 wt.% Ni and Cu-14.4 wt.% Al-5.5 wt.% Ni, were used.