Simulation Of Local Atomic Structure Of Zr-based Amorphous Alloys During Rapid Solidification

Amorphous alloys have broad application prospects in many fields due to their excellent physical,chemical and mechanical properties.Zr-based amorphous alloys have attracted more and more attention because of their high strength,high toughness,high elastic limit,high corrosion resistance and excellent glass forming ability.The excellent properties of Zr-based amorphous alloys are related to their special atomic structure.Although the research on the atom structure of amorphous alloys has never stopped,many problems,such as the reason of glass transition,have not been clearly understood.In this paper,Zr-Ni binary amorphous alloy and Zr-Ni-Al ternary amorphous alloy are studied.The molecular dynamics method is used to study the effect of cooling rate and pressure on the atomic structure of Zr₆₇Ni₃₃3 amorphous alloy,investigating the composition effect of Al atoms on the microstructure of Zr₆₇Ni_33-xAl_x?x=5,10,15,20?amorphous alloy.According to the research direction,the article can be divided into the following three parts:?1?The reduction of cooling rate can reduce the glass transition temperature and free volume of Zr₆₇Ni₃₃3 system to promote the bonding between Zr-Zr and Zr-Ni atoms.The lower cooling rate promotes the entry of atoms into the Zr-centered cluster,while inhibiting the entry of atoms into the Ni-centered cluster,thus improving the orderliness and stability of the system structure.?2?With the increase of pressure,the glass transition temperature of Zr₆₇Ni₃₃3 system also increases but the free volume content decreases.As the pressure increasing,the short-range order increases gradually,and the five-time symmetry becomes higher,that is to say,the more potent the inhibition of crystallization becomes,the more powerful the amorphous formation ability is.Atomic diffusion becomes more and more difficult,however,the phenomena of system dynamics slowdown and dynamic inhomogeneity are more and more intense.?3?With the increase of Al atom content,the glass transition temperature of amorphous alloy Zr₆₇Ni_33-xAl_x?x=5,10,15,20?raises.As the content of Al increases,the content of clusters centered on Zr atoms rises,yet the content of clusters of central atoms with Ni and Al reduces.Obviously,with the increase of Al content,the cluster size centered on Zr atom becomes larger,the cluster size centered on Ni and Al atom becoming smaller.At the same time,the number of three atoms shared among clusters increases gradually.With the reduction of the connection modes sharing two atoms,the atomic structure of amorphous alloys is more orderly and stabler.