New Class of Plastic Bulk Metallic Glass

Abstract

An intrinsic plastic Cu(45)Zr(46)Al(7)Ti(2) bulk metallic glass (BMG) with high strength and superior compressive plastic strain of up to 32.5% was successfully fabricated by copper mold casting. The superior compressive plastic strain was attributed to a large amount of randomly distributed free volume induced by Ti minor alloying, which results in extensive shear band formation, branching, interaction and self-healing of minor cracks. The mechanism of plasticity presented here suggests that the creation of a large amount of free volume in BMGs by minor alloying or other methods might be a promising new way to enhance the plasticity of BMGs.

Local microstructure evolution at shear bands in metallic glasses with nanoscale phase separation

“…2 , inset top-left) when testing was stopped at a plastic strain of 110%. This extraordinary plasticity is comparable with that for bulk MGs and their composites reported elsewhere 27 40 41 42 43 44 45 46 47 . Such large compressive strains appear to be facilitated by inhomogeneity, for which phase separation, as in the present plastic glasses, is one possible origin.…”

“…3(a,b) ). The apparent dissolution of nanospheres inside the band, while preserving the glassy state, contrasts with the reported formation of nanocrystals within shear bands 8 12 47 48 .…”

Local microstructure evolution at shear bands in metallic glasses with nanoscale phase separation

“…2 , inset top-left) when testing was stopped at a plastic strain of 110%. This extraordinary plasticity is comparable with that for bulk MGs and their composites reported elsewhere 27 40 41 42 43 44 45 46 47 . Such large compressive strains appear to be facilitated by inhomogeneity, for which phase separation, as in the present plastic glasses, is one possible origin.…”

“…3(a,b) ). The apparent dissolution of nanospheres inside the band, while preserving the glassy state, contrasts with the reported formation of nanocrystals within shear bands 8 12 47 48 .…”

Nanoindentation investigation on the creep mechanism in metallic glassy films

“…Here, the same effect of Ti addition would be concluded indirectly from the smaller-sized veinpattern fracture morphology. The SEM observations implies an enhanced ductility in Cu-Zr-Al film with Ti addition [20], which was consistent with Chen's [12]. What is more, the thinner smooth region indicates a relatively weaker resistance to the plastic shearing in Cu-Zr-Al-Ti film.…”

“…The STZ volumes of the both samples are consistent with those reported by experimental calculation and simulation prediction [13,29,30]. 60% enlargement on the STZ volume, from 0.552 nm 3 to 0.884 nm 3 with 1.5% Ti addition, could explain the significant improvement of ductility in the bulk one in turn [7,12]. Large STZs can produce large internal concentrations which facilitate activation of surrounding STZs, promoting multiple shear bands.…”

“…2(b). In the bulk sample, Ti addition on Cu-Zr-Al metallic glass effectively increased the density of shear bands during plastic deformation [12]. Here, the same effect of Ti addition would be concluded indirectly from the smaller-sized veinpattern fracture morphology.…”

Local microstructure evolution at shear bands in metallic glasses with nanoscale phase separation

“…2 , inset top-left) when testing was stopped at a plastic strain of 110%. This extraordinary plasticity is comparable with that for bulk MGs and their composites reported elsewhere 27 40 41 42 43 44 45 46 47 . Such large compressive strains appear to be facilitated by inhomogeneity, for which phase separation, as in the present plastic glasses, is one possible origin.…”

“…3(a,b) ). The apparent dissolution of nanospheres inside the band, while preserving the glassy state, contrasts with the reported formation of nanocrystals within shear bands 8 12 47 48 .…”

Nanoindentation investigation on the creep mechanism in metallic glassy films

“…Here, the same effect of Ti addition would be concluded indirectly from the smaller-sized veinpattern fracture morphology. The SEM observations implies an enhanced ductility in Cu-Zr-Al film with Ti addition [20], which was consistent with Chen's [12]. What is more, the thinner smooth region indicates a relatively weaker resistance to the plastic shearing in Cu-Zr-Al-Ti film.…”

“…The STZ volumes of the both samples are consistent with those reported by experimental calculation and simulation prediction [13,29,30]. 60% enlargement on the STZ volume, from 0.552 nm 3 to 0.884 nm 3 with 1.5% Ti addition, could explain the significant improvement of ductility in the bulk one in turn [7,12]. Large STZs can produce large internal concentrations which facilitate activation of surrounding STZs, promoting multiple shear bands.…”

“…2(b). In the bulk sample, Ti addition on Cu-Zr-Al metallic glass effectively increased the density of shear bands during plastic deformation [12]. Here, the same effect of Ti addition would be concluded indirectly from the smaller-sized veinpattern fracture morphology.…”

Local microstructure evolution at shear bands in metallic glasses with nanoscale phase separation

“…2 , inset top-left) when testing was stopped at a plastic strain of 110%. This extraordinary plasticity is comparable with that for bulk MGs and their composites reported elsewhere 27 40 41 42 43 44 45 46 47 . Such large compressive strains appear to be facilitated by inhomogeneity, for which phase separation, as in the present plastic glasses, is one possible origin.…”

“…3(a,b) ). The apparent dissolution of nanospheres inside the band, while preserving the glassy state, contrasts with the reported formation of nanocrystals within shear bands 8 12 47 48 .…”

Nanoindentation investigation on the creep mechanism in metallic glassy films

“…Here, the same effect of Ti addition would be concluded indirectly from the smaller-sized veinpattern fracture morphology. The SEM observations implies an enhanced ductility in Cu-Zr-Al film with Ti addition [20], which was consistent with Chen's [12]. What is more, the thinner smooth region indicates a relatively weaker resistance to the plastic shearing in Cu-Zr-Al-Ti film.…”

“…The STZ volumes of the both samples are consistent with those reported by experimental calculation and simulation prediction [13,29,30]. 60% enlargement on the STZ volume, from 0.552 nm 3 to 0.884 nm 3 with 1.5% Ti addition, could explain the significant improvement of ductility in the bulk one in turn [7,12]. Large STZs can produce large internal concentrations which facilitate activation of surrounding STZs, promoting multiple shear bands.…”

“…2(b). In the bulk sample, Ti addition on Cu-Zr-Al metallic glass effectively increased the density of shear bands during plastic deformation [12]. Here, the same effect of Ti addition would be concluded indirectly from the smaller-sized veinpattern fracture morphology.…”