W0279

Internal Stresses in Bulk Metallic Glasses. E. Üstündag¹, B. Clausen², S. Y. Lee¹, G. S. Welsh¹, I. Halevy³, Th. Proffen², ¹Dept. of Materials Science, California Inst. of Technology, Pasadena, CA 91125, ²Los Alamos Neutron Science Center, Los Alamos National Laboratory, Los Alamos, NM 87545, ³Physics Dept., Negev Nuclear Research Center, 84190 Beer-Sheva, Israel.

Bulk metallic glasses (BMGs) are recent entries into the structural materials field due to the development of new alloys that yield a glassy structure even with “conventional” metal processing such as casting. BMGs possess some unique properties as engineering materials: very high strength (above 2 GPa), good fracture toughness (20-55 MPa.m^1/2), a high specific strength, excellent wear and corrosion resistance, and a high elastic strain limit (around 2%). Composites made of BMG matrices reinforced with metallic fibers or inclusions possess superior mechanical properties compared to monolithic BMGs. However, the thermal expansion mismatch between the reinforcements and the matrix as well as the elastic and plastic incompatibilities between the two phases generate internal stresses. Neutron and high-energy X-ray diffraction techniques were employed to characterize these stresses in the crystalline reinforcements. The lattice strain data were used to develop mechanics models that describe the behavior of each phase. Preliminary results will also be presented about the response of the amorphous matrix to applied loading as quantified with the analysis of its PDF patterns.