Nanocrystallization in Al-Based Amorphous Al—Ni—Fe—La Alloys

摘要

The structure, phase transformations, and microhardness in an amorphous state and after intensive elastic shearing deformation under a pressure of 4 and 8 GPa have been studied in alloys of the Al—Ni- Fe—La system, where complex alloying provides the capability of obtaining an amorphous state by means of quenching at a rate of 10~6 K/s. It has been demonstrated that multiphase nanocrystallization is established in the structure upon thermal treatment and elastic deformation, together with the formation of nanograins of various intermetallic compounds and aluminium. For the first time it has been discovered that crystallization is preceded by segregation in an amorphous matrix with the formation of two amorphous phases, one of which is enriched in aluminium and the other in nickel and lanthanum. It has been demonstrated that crystallization starts in the phase enriched with nickel and lanthanum regardless of the treatment type. The thermal stability and microhardness of the alloys have been determined as a function of their alloying. The results have been compared with the available published data on the mechanical properties of similar alloys.