First-principles Verification Of Grain Refinement Mechanism Of Aluminum And Aluminum Alloys

Al-Ti-B grain refiner refinement of aluminum and aluminum alloy refinement mechanism has been in dispute.It is recognized that the morphology,size and distribution of Al₃Ti and TiB₂ have a crucial role in refinement process.In this paper,the first-principles calculation method is used to study the bonding potential of aluminum grains and the above two particles from the energy angle and interface bonding;The sub eutectic Al-Si alloy is often called the thinning agent "poisoning" phenomenon after the treatment of Al-Ti-B grain refinement agent.Therefore,a new type of refiner Al₃Nb with the same crystal structure as Al₃Ti crystal was found.The interfacial properties of Al₃Nb/Al binding interface are calculated.By calculating the interfacial properties of Al/Al₃Ti,Al/TiB₂,Al₃Ti/TiB₂,the longitudinal comparison can be found,no matter what type of interface,The stacking model of the center always has more adhesive work,smaller interface energy,stronger interface bonding characteristics than other stacking models?such as the top and the bridge stacking?;The Al?110?/Al₃Ti?110?interfacial model has smaller interfacial energy and stronger interfacial binding ability.Compared with the interface of Al/Al₃Ti and Al/TiB₂,the interface of Al₃Ti?112?/TiB₂?0001?has the lowest interfacial energy.It is shown that the?112?plane of Al₃Ti preferentially binds to the?0001?plane of TiB₂ under the same conditions,and then the Al₃Ti is used as the nucleus for the formation of Al₃Ti,which reveals the theory of particles from microscopic view;By calculating the six interfaces of Al?001?/Al₃Nb?001?,it is found that the Al+Nb-and Al-modes have a more stable structure.For the same cut-off mode of the different stacking interface,the interface stability decreased as the order of center,bridge and top.The interfacial model of Al+Nb-is always stable than that of Al-.The interactions of the interface of Al+Nb-are mainly from the covalent bond formed by Al-3p and Nb-4d electrons and the weak metal bonds.The function of the interface between the three interface models of Al-mainly comes from the metal bond formed between Al-3p electrons,and there is also a weak covalent bond..