Lecture06 - ME 382 Lecture 06 Crystal Structure Modulus of...

Info icon This preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
ME 382 Lecture 06 17/ix/07 1 Crystal Structure Modulus of a material depends on Bond strength Packing of atoms (bond density) Density of a material depends on Atomic weight of atoms Packing of atoms Two forms of packing solids: amorphous and crystalline Amorphous : Position of atoms completely random Structure like a liquid, but resists shear like a solid E.g. , window glass, metallic glasses, amorphous polymers (PMMA, PC) Crystalline: Atoms are in well-ordered positions relative to each other E.g. , most metals and ceramics, and crystalline regions in some polymers Ordered region where atoms have the same crystal structure and the same orientation Silicon wafers are huge single crystals Most engineering materials are a collection of crystals - polycrystalline Individual crystals are known as grains (typically nm to cm in size) Atomic packing in crystals Can be useful to think of atoms as hard spheres of radius r o Random arrangement of spheres gives a packing density of 64 %
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern