Dynamic behavior of a Ce-Al bulk metallic glass

[摘要] The mechanisms of stress relaxation in metallic glasses under high strain rates are an area of active study. The lack of extended structure forces strain accommodation through alternative modes to slip For example, amorphous Ce3Al has been shown to undergo a phase transition to the crystalline FCC Ce3Al at 25 GPa under quasistatic loading. Whether this mechanism extends to high strain rates has yet to be determined. We present results of an initial study into the ultrafast deformation characteristics of a Ce-Al bulk metallic glass. Using the Janus laser at the Jupiter Laser Facility (LLNL), thin targets 30 micron in thickness were shocked over a range of pressures up to 30 GPa. The velocity of the target rear surface was measured using a line-imaging VISAR to reveal features in the wave profile attributed to stress relaxation. In addition, experiments were performed on crystalline forms of Ce-Al prepared through heat treatment of the amorphous material. Preliminary results reveal a distinct precursor wave above and below 1.5 GPa, which gives way to a complex multiwave structure around 1.5 GPa, most likely indicative of a polyamorphic transition.

[发布机构] Institute of Shock Physics, Imperial College London, SW7 2AZ, United Kingdom^1;Georgia Institute of Technology, Atlanta; GA; 30332, United States^2;Lawrence Livermore National Laboratory, Livermore; CA; 94550, United States^3

[关键词] Bulk metallic glass;Dynamic behaviors;Extended structures;High strain rates;Polyamorphic transitions;Quasi-static loading;Strain accommodations;Ultrafast deformation