Effect of Microstructural Change on High-Temperature Deformation in Pre-Annealed Zr<SUB>65</SUB>Al<SUB>10</SUB>Ni<SUB>10</SUB>Cu<SUB>15</SUB> Bulk Metallic Glass

Abstract

The effect of the microstructural change on the high-temperature tensile deformation behavior in the supercooled liquid region is investigated in the pre-annealed Zr 65 Al 10 Ni 10 Cu 15 bulk metallic glass. The microstructure before the tensile test on the specimen annealed at 673 K for 1.8ks shows that a small amount of icosahedral phase precipitates and a large amount of amorphous phase still remains. On the contrary, the specimen annealed at 673 K for 2.7 ks shows that a large amount of icosahedral phase precipitates and the presence of amorphous phase is hardly noticeable. From the fact that flow stress of the specimen annealed at 673 K for 2.7 ks increases in comparison with that of asreceived specimen as well as the specimen annealed at 673 K for 1.8 ks in the tensile test, it seems that the deformation behavior in the tension tests is greatly influenced by the difference in the degree of the precipitation of icosahedral phase. Since the m value is about 0.5 and many grain boundaries of icosahedral phase are formed in the specimen annealed at 673 K for 2.7 ks, the interaction between the icosahedral phase particles must be the cause of increase in initial stress. Accordingly, the microstructure of the gage section after tensile test in the specimen annealed at 673 K for 1.8 ks shows that the large amount of icosahedaral phase precipitates in the amorphous matrix. The strain hardening must be caused by the interaction between the icosahedral phase particles whose precipitation and growth are enhanced by deformation.