Dr. Alagiriswamy A A, Asst. Professor, Dept. of Physics, SRM-U, Chennai Dr. Alagiriswamy A A, (M.Sc, PhD, PDF) Asst. Professor (Sr. Grade), Dept. of Physics & Nanotechnology, SRM-University, Kattankulathur campus, Chennai Mar. 18/2014 UNIT III Lecture 2

Dr. Alagiriswamy A A, Asst. Professor, Dept. of Physics, SRM-U, Chennai  Shape memory alloys (SMAs)  Metallic glasses or amorphous metals  examples, features, preparation, applications  Composites  Features, examples, products  Advanced ceramics  Examples  Categories, preparation (processing techniques)  properties  features, examples Outline

Dr. Alagiriswamy A A, Asst. Professor, Dept. of Physics, SRM-U, Chennai Stents as SMAs Before I proceed Ability to bend, stay bent, and regain its shape Uses internal atomic arrangement to recognize their sh apes Austentite (high temperature cubic phase) & Martensit e (low temperature deformed or twinned phase)

Dr. Alagiriswamy A A, Asst. Professor, Dept. of Physics, SRM-U, Chennai Metallic Glass: A Revolution of Metallurgy Metallic glass = Amorphous metal –Metals (have long range order, ductility, malleability, lusture) –Glasses (lack of long range order – short range order, no crystallinity feat ures ) –It's called metallic glass, and it shines like a mirror, but when you drop a pie ce of it to the floor, it doesn't break. In fact, it bounces--wildly--thanks to its unusual atomic structure – can it be called as a liquid metal –Conventional metals crystallize when cooled from a liquid to a solid. But metallic glass cools to an amorphous (glassy) structure, making it much stronger, lighter, and springier than other metals--and virtually corrosion-proof – low hysteresis (may be a soft magnetic)

Dr. Alagiriswamy A A, Asst. Professor, Dept. of Physics, SRM-U, Chennai X-ray spectrum of ……….. (a) crystalline material and (b) amorphous material

Dr. Alagiriswamy A A, Asst. Professor, Dept. of Physics, SRM-U, Chennai (a) Mechanical properties Unique features of MG……….. (b) Magnetic properties

Dr. Alagiriswamy A A, Asst. Professor, Dept. of Physics, SRM-U, Chennai More interesting features of MG …… Imagine a razor blade that stays super sharp for a year. A golf club so springy it can drive a ball farther than a titanium club. An artificial hip implant that is stronger and more flexible than current implants. A cell phone case that is almost indestructible

Dr. Alagiriswamy A A, Asst. Professor, Dept. of Physics, SRM-U, Chennai Fabrication of MG …

Dr. Alagiriswamy A A, Asst. Professor, Dept. of Physics, SRM-U, Chennai Advanced Ceramic Materials Non-metallic elements, need not be inorganic Hard and brittle, toughness, Chemically inert, having high melting points Electrically/thermally considered to be insulators Ceramic materials  Traditional ceramics (bricks, porcelain)  Advanced ceramics (SiC, Si 3 N 4, Al 2 O 3 )

Dr. Alagiriswamy A A, Asst. Professor, Dept. of Physics, SRM-U, Chennai A few applications of Adv. Cer…..

Dr. Alagiriswamy A A, Asst. Professor, Dept. of Physics, SRM-U, Chennai Comparison metals v ceramics Ceramics Metals

Dr. Alagiriswamy A A, Asst. Professor, Dept. of Physics, SRM-U, Chennai Processing of advanced ceramics Material preparation –Milling/sizing to form desired particle size Forming or casting –Pressing into a die – to form a shaped product Thermal treatment –Drying: to remove water from the plastic and the proces s is carried out in the range 200 to 3000C. –Sintering: small particles of a material bonded together - solid-state diffusion. During this process ceramic poro us product is made into a dense coherent product.

Dr. Alagiriswamy A A, Asst. Professor, Dept. of Physics, SRM-U, Chennai

Composites A composite is basically a material that contains both a reinforcing material to provide strength and stiffness and a matrix material to surround and hold the reinforcement together. Natural composites: –Wood (cellulose/lignin) –Bone (apatite/collagen) –Nacre ( Mother of pearl) (Aragonite/protein) –Granite (quartz, feldspars…)

Dr. Alagiriswamy A A, Asst. Professor, Dept. of Physics, SRM-U, Chennai Engineered materials –(reinforcing phase, matrix phase) –Orthotropic :- depends on the direction of the exter nal load applied –Difficult to explain the mechanical properties –Shock/impact creates failure at micro/macro level –Fiber reinforced, glass reinforced, carbon reinforced composites features

Dr. Alagiriswamy A A, Asst. Professor, Dept. of Physics, SRM-U, Chennai What are the advantage of composites ? Light weight High strength & stiffness Reinforcement fibres can be arranged to follow the direction of principle loads and stresses Good fatigue resistance Very low coefficient of thermal expansion Good environmental and corrosion resistance The ability to manufacture complex shapes by moulding results in cost-eff ective production

Dr. Alagiriswamy A A, Asst. Professor, Dept. of Physics, SRM-U, Chennai

Applications as

Dr. Alagiriswamy A A, Asst. Professor, Dept. of Physics, SRM-U, Chennai Applications as

Dr. Alagiriswamy A A, Asst. Professor, Dept. of Physics, SRM-U, Chennai

Thanks for the kind attention