Study Of The Crystallization Behavior Of Zr_41.3Ti_14.2Cu_12.8Ni_10.3Be_21.4 Bulk Metallic Glasses

The crystallization behavior, mechanical properties and crystallization kinetics of Zr41.3Ti14.2Cu12.8Ni10.3Be21.4 bulk metallic glasses (BMGs) were investigated in detail. The influence of high-density pulsing current on the structural relaxation and crystallization behavior has been discussed.Based on experimental research, it has been found that pulsing current can promote the crystallization transition of the BMGs. With appropriate parameters, fine (about 5-12 nm) and uniformly distributed nanocrytals have been formed within the amorphous matrix. Under the action of high-density pulsing current the Zr41.3Ti14.2Cu12.8Ni10.3Be21.4 BMGs can be nearly fully crystallized in a very short time (about 44s).Under the same crystallization conditions, the pretreatment of the Zr41.3Ti14.2Cu12.8Ni10.3Be21.4 BMGs by high-density pulsing current can increase the volume fraction of the precipitated nanocrystals within the amorphous matrix and the strength of the Zr41.3Ti14.2Cu12.8Ni10.3Be21.4 alloy. It also increased the volume fraction of the crystalline phases which corresponded to the ductile-brittle transition of the alloy.The result of thermal analysis shows that the pretreatment of the Zr41.3Ti14.2Cu12.8Ni10.3Be21.4 BMGs by pulsing current has significant influence on the glass transition behavior and crystallization kinetics of the alloy. Quite different from the effect of conventional pre-annealing treatment, when the Zr41.3Ti14.2Cu12.8Ni10.3Be21.4 BMGs was treated by high-density pulsing current, its glass transition temperature Tg, onset crystallization temperature Tx and crystallization peak temperature Tpi were decreased obviously while the supercooled liquid region (T was almost unchanged. In addition, the apparent activation energy of the glass transition was decreased significantly while the apparent activation energy of the crystallization was nearly unchanged. The variation of short-range order of atoms in the amorphous alloy and the structural relaxation induced by pulsing current are believed to be responsible for this phenomenon. The detailed study of the influence of pulse current on the glass transition and crystallization behavior of the BMGs is very important and necessary, since it is very helpful and meaningful for understanding the nature of BMGs' glass transition and crystallization behavior, and for improving the properties of bulk metallic glasses by controlling of the crystallized microstructures.