1. Metallic Glasses in Cell Phones Angelika Franz

2. Outline what is a metallic glass structure properties processing cell phone cases cell phone hinges

3. Metallic Glass I amorphous material: atoms “frozen” in non-crystalline form lack long-range atomic order first formed in 1957 by Duwez by rapid quenching  gold-silicon alloy  only very thin, small samples could be produced (order or micrometers)

4. Metallic Glass II 1990: found new alloys to form bulk metallic glasses  typically used three or more metallic elements cooling rates needed decreased could produce samples on order of centimeters Zr-Ti-Cu-Ni-Al alloy

5. Structure I first believed atoms were randomly packed together densly like hard spheres in a liquid  solvent atoms randomly arranged with solute atoms fitting into open cavities now believe short-range, even medium- range order exists in materials

6. Structure II form nanoscale “superclusters”  difference in size between alloyed elements make solvent atoms cluster around solute atoms  Kasper polyhedra: 7 to 15 atoms arranged around central atom  polyhedra shape depends on size of constituent atoms  range of coordination numbers: different polyhedra exist within same material

7. Structure III was proposed that clusters conform to fcc lattice for closest-packing with strain factor to limit order to 1-1.5 nm actually found clusters pack into icosahedral structures usually 1.5 nm wide  creates cavities into which extra solute atoms can pack

8. Properties I lack of crystallinity means lack of defects  gives rise to interesting properties stronger and lighter than metals tough: resistant to fracture  unlike ceramic glass is not brittle easily heated, softened and molded into shapes

9. Properties II uncorrosive not transparent very high elastic strain limit  makes material bouncy

10. Processing I formed by quenching at rates of 1-100 degrees Celsius per second  used to be 1 million degrees Celsius per second prevent atoms from forming into crystalline structure, instead freeze into liquid-like structure limits size and shape of material produced

11. Processing II near net-shape casting  alloy is cast near to final shape injection molding  metallic glass is heated until it softens and can flow into the mold physical vapor deposition ion irradiation mechanical alloying

12. Cell Phone Cases I alloy of zirconium, titanium, copper, nickel and beryllium produced using near net-shape casting smaller, thinner designs with greater protection of internal components

13. Cell Phone Cases II sleek metallic surface scratch and corrosion resistant ~2.5 times strength of titanium alloy ~1.5 times hardness of stainless steel non-reactive thinner walls with greater strength

14. Cell Phone Hinges deformation resistant  high yield strength and elasticity more durable than conventional materials very resilient to impact and daily wear-and-tear reliable in repeated load-bearing conditions

15. References http://www.liquidmetal.com/ http://www.jhu.edu/news/home06/jan06/glass.html http://engr.oregonstate.edu/momentum/stories/liquid_metal.ht ml http://www.jhu.edu/matsci/people/faculty/hufnagel/background. html http://www.nature.com/nature/journal/v439/n7075/full/439405a.html;jsessionid=396A417548AD57212FA5DAF138B540CA http://www.sciencedaily.com/releases/1998/03/980331074950. htm B. Van Aken, P. de Hey, and J. Sietsma: Structural relaxation and plastic flow in amorphous La 50 Al 25 Ni 25. Mater. Sci. Eng. A 278, 247 (2000). http://www.sciwrite.caltech.edu/journal03/owensmichael.html