材料科学新进展_英文课程课件_Amorphous metals_2015.pdf

Amorphous alloys Amorphous alloys Amorphous Alloys (Metallic Glasses) 1 Amorphous alloys Amorphous alloys What is metallic glass (MG)?  Metallic species “frozen” in amorphous glassy state.  When a liquid is cooled below its melting temperature TM ……  Typically, as the supercooled liquid’s temperature decreases, so do its enthalpy and volume.  At what’s known as the glass transition temperature T , the atoms in G the liquid become so tightly packed that they can no longer easily rearrange themselves.  In that glassy state, the system behaves like a solid, although liquid-like disorder is “frozen” into its structure.  The challenge, then, is to supercool the liquid from TM to TG so fast that there’s no chance for a crystalline phase to nucleate and grow. 2 Physics Today Feb.(2013)32 Amorphous alloys Amorphous alloys 800 IntroductionStructure features ) Features of amorphous alloys s 600 p c ( y t 400  Long-range disorder i  Long-range disorder s