Local atomic structure of amorphous and crystalline alloys: Computer simulation

The microscopic stresses defined at each atom, or the atomic level stresses, are effective parameters to describe the local variations in the atomic arrangement in liquids and glasses. We have calculated them for model binary alloy systems both in the amorphous and in the crystalline (fcc and bcc) states. It was found that alloying two elements does not change the average atomic level stresses in the amorphous state when normalized by the elastic modulus, while in the crystalline state alloying sharply increases the stresses, in agreement with the theoretical prediction. Some of the basic issues regarding the nature of the amorphous alloys, namely the glass transition and the criteria for glass formation, are discussed based upon these results.