Int J Fract (2010) 163:217–224 DOI 10.1007/s10704-009-9437-1 ORIGINAL PAPER Dynamic fracture and spall in aluminum with helium bubbles Benny Glam · Shalom Eliezer · Daniel Moreno · Lior Perelmutter · Morris Sudai · Dan Eliezer Received: 1 March 2009 / Accepted: 7 December 2009 / Published online: 12 January 2010 © Springer Science+Business Media B.V. 2010 Abstract Investigation of the dynamic properties of aluminum targets with helium bubbles is presented. The targets were obtained by melting pure aluminum with 0.15% wt. 10 B powder. The solid targets were neu- tron irradiated to get homogeneous helium atoms inside the aluminum boron 10 matrix according to the reaction 10 B+n → 7 Li+ 4 He. Helium atoms further accumu- lated into bubbles by diffusion in the bulk aluminum. Shock wave experiments were performed by acceler- ating the aluminum impactor into different targets: (1) pure aluminum, (2) Al- 10 B, and (3) Al- 10 B with dif- ferent radii and concentrations of helium bubbles. The spall strength was calculated and analyzed from the free surface velocity measurements. It was found that the addition of 10 B in pure aluminum reduces the spall strength of the material by 25–32%. However, irradi- ated sample with helium bubbles was found to have higher spall strength compared to samples without bub- bles. This finding was reconstructed by numerical sim- ulations. The impacted targets were collected after the impact experiments and examined by TEM. These tar- gets were compared to TEM pictures before the impact. The number of helium atoms in the bubbles was calcu- lated from the electron energy loss spectrum (EELS). B. Glam (B ) · S. Eliezer · D. Moreno · L. Perelmutter · M. Sudai Soreq Nuclear Research Center, Yavne 81800, Israel e-mail: glam@bgu.ac.il; benny.glam@gmail.com B. Glam · D. Eliezer Ben-Gurion University of the Negev, Beer-Sheva, Israel TEM comparison between the pre-impacted and the impacted targets shows bubbles coalescence and EELS measurements demonstrate a reduction of the helium atoms concentration in the bubbles from ∼ 10 28 m -3 before the impact to ∼10 27 m -3 after the impact. Keywords Helium bubbles · Spall · Aluminum · TEM · EELS 1 Introduction Defects in materials, such as cracks in brittle materi- als and voids in ductile metals, are known to change the material’s strength for spall (Eliezer et al. 1990; Grady 1988). Additional substances in a metal, even in small amounts, change the static and dynamic behav- iors (Chen et al. 2006; Trivedi et al. 2007). Furthermore, low porosity of 3.3% in aluminum was also found to change the dynamic response (Wang et al. 2007). Static research showed that the introduction of helium atoms in metals is very significant, since their precipitation into bubbles can substantially deteriorate the mechanical properties of a material (Trinkaus and Singh 2003). Dynamic research in this field is quite rare and therefore investigation of the influence of helium bubbles in metal on its dynamic properties is important. In most of the research on helium–metal interac- tion, the helium bubble distribution in metal is accom- plished by helium implantation (Foeman and Singh 1985; Marian et al. 2002; Moreno and Eliezer 1996) 123