L Journal of Alloys and Compounds 310 (2000) 324–329 www.elsevier.com / locate / jallcom Influence of high-energy impact actions on the elastic and anelastic properties of martensitic Cu–Al–Ni crystals a, a b a,c a a * Yu. Emel’lyanov , S. Golyandin , N.P. Kobelev , S. Kustov , S. Nikanorov , G. Pugachev , a a b d e K. Sapozhnikov , A. Sinani , Ya.M. Soifer , J. Van Humbeeck , R. De Batist a A.F. Ioffe Institute, Politekhnicheskaja 26, 194021 St. Petersburg, Russia b Institute of Solid State Physics, 142432 Chernogolovka ( Moscow region), Russia c ´´ IGA-DP , Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne, Switzerland d Departement MTM, Katholieke Universiteit Leuven, De Croylaan 2, B-3001 Leuven, Belgium e IMS, University of Antwerpen ( RUCA), Middelheimlaan 1, B-2020 Antwerp, Belgium Abstract The influence of high-energy impact shock-wave loading on the microplasticity and macroscopic performance of the Cu–Al–Ni 9 crystals in the b martensitic phase has been studied. Elastic and anelastic properties of quenched and aged polyvariant single crystals 1 before and after impact shock-wave loading were measured in the temperature range 80–300 K, at a frequency of about 100 kHz in the strain amplitude-independent and amplitude-dependent ranges by means of the composite oscillator technique, and in the MHz frequency range using the pulse–echo technique. High-velocity impact loading of the specimens was realised by plane shock-waves with stress 26 pulses with a duration of |2?10 s and stress amplitudes up to 5 GPa. A pronounced influence of impact shock-wave loading on the 9 elastic and anelastic properties of the b martensite has been observed. A strongly marked softening of the material and an enhancement 1 of damping properties are revealed up to the highest stress pulse amplitudes. This behaviour differs fundamentally from the one observed in ‘ordinary’ fcc metals. Changes of the defect structure induced by shock-wave loading, which may be responsible for the observed phenomena, have been discussed.  2000 Published by Elsevier Science S.A. Keywords: Metal; Mechanical properties; Elasticity; Ultrasonics 1. Introduction phase. The 6 mm diameter rod was oriented along the [100] direction of the initial b phase. The rod was High-energy impact action may produce changes on the quenched from 9508C into water at room temperature. structure as well as on the elastic, anelastic and plastic Dynamic compression tests were performed by Kolsky’s behaviour of materials undergoing martensitic transforma- method using a composite Hopkinson’s rod [1], which tions. The physics of the processes is not known. The consists of a short sample, located between two 1 m310 present work is an investigation of the effect of impact mm, high-strength steel rods. There are two tensometer wave loading on the elastic and the macro- and microplas- gauges on these rods. Data about the deformation pulses of tic properties of Cu–Al–Ni single crystals. the rods are stored in a computer for later use. The striker is a 150 mm steel rod. During its flight in the barrel of a gas gun the striker crosses two light beams of photo 2. Experimental gauges to measure velocity, which for stress–strain tests reached 34.5 m / s. Results are presented as s vs. e and Samples for all the present investigations, carried out by de /dt vs. e curves. different methods, were cut from one single crystal rod of To investigate the effect on anelasticity of the Cu–Al– 9 Cu–13.2 wt.% Al–4.0 wt.% Ni in the b martensitic Ni alloy impact shock-wave loading was made by a striker 1 in the shape of a little hollow cylinder accelerated by a gas gun to velocities in the range from 50 to 500 m/s. The plate-shaped samples were held in a special brass holder, *Corresponding author. which acoustic stiffness is close to that of the Cu–Al–Ni 0925-8388 / 00 / $ – see front matter  2000 Published by Elsevier Science S.A. PII: S0925-8388(00)00960-9