TEST ENVIRONMENTS AND MECHANICAL-PROPERTIES OF ZR-BASE BULK AMORPHOUS-ALLOYS

The mechanical properties of two Zr-base bulk amorphous alloys (BAA), Zr-1oAl-30Cu-5Ni (BAA-10) and Zr-10Al-5Ti-17.9Cu-14.6Ni (BAA-11), were studied by both tensile and compressive tests at room temperature in various test environments. The BAA ingots up to 7 mm in diameter were successfully produced by both are melting and drop casting and inducti on melting and injection casting. The BAA specimens deformed mainly el astically, followed by catastrophic failure along shear bands. Examina tion of the fracture region revealed ductile fracture features resulti ng from a substantial increase in temperature, which was attributable to the conversion of the stored elastic strain energy to heat. Surpris ingly, ''liquid droplets'' located at major shear-band cracks adjacent to the fracture section were observed, indicating the occurrence of l ocal melting during fracture. The angle orientation of shear bands, sh ear-band cracks, and fracture surfaces relative to the stress axis is quite different for BAA specimens tested in tension and compression. T his suggests that both shear stress and normal stress may play a role in developing shear bands during plastic deformation. The tensile prop erties of BAAs were found to be insensitive to the test environment at room temperature. However, the reaction of BAAs with distilled water and heavy water was detected by laser desorption mass spectrometry (LD MS). These results suggest that moisture-induced hydrogen embrittlemen t in BAAs may be masked by catastrophic fracture following shear bands .