The Effect of Atomic-Scale Open-Volume on Flow and Fracture Processes in a Zr-Ti-Ni-Cu-Be Bulk Metallic Glass

2002 ◽  
Vol 754 ◽  
Author(s):  
Daewoong Suh ◽  
Reinhold H. Dauskardt
Keyword(s):  
Metallic Glass ◽  
Viscous Flow ◽  
Bulk Metallic Glass ◽  
Glass Structure ◽  
Fracture Morphology ◽  
Atomic Scale ◽  
Open Volume ◽  
Strain Fracture ◽  
Crack Growth Rates ◽  
Fracture Processes

ABSTRACTEffects of atomic-scale open-volume regions in metallic glass structure on the flow and fracture behavior of a Zr-Ti-Ni-Cu-Be bulk metallic glass were examined. Studies of relaxation time scales showed that atomic arrangement processes for viscous flow were significantly retarded with annealing. Plane strain fracture toughness was significantly decreased and fatigue crack crack-growth rates were dramatically increased, indicating degradation of resistance to crack extension as a result of annealing. Fracture morphology completely changed from vein patterns to cleavage-like features with little evidence of plasticity with annealing. The positron lifetime and Doppler broadening experiments revealed decreased open-volume regions as a result of annealing. The loss of stress relief ability by retarded crack tip viscous flow as a result of the anneal-out of open-volume regions is believed to contribute to observed annealing embrittlement.

Machinability of BMG

2012 ◽  
Vol 521 ◽  
pp. 225-253
Author(s):  
Mustafa Bakkal
Keyword(s):  
High Temperature ◽  
Metallic Glass ◽  
Viscous Flow ◽  
Bulk Metallic Glass ◽  
Light Emission ◽  
Cutting Speed ◽  
Good Surface ◽  
High Cutting Speed ◽  
Exothermic Chemical Reaction ◽  
Good Surface Roughness

This chapter covers the series of machinability evaluation test result and discussions of Zr52.5Ti5Cu17.9Ni14.6Al10bulk metallic glass (BMG). These tests are lathe turning, drilling, milling and preliminary level grinding tests. In the continuous machining methods such as turning, drilling and grinding of BMG, above a threshold cutting speed, the low thermal conductivity of BMG leads to chip temperatures high enough to cause the chip oxidation and associated light emission. The high temperature produced by this exothermic chemical reaction causes crystallization within the chips. Chips morphology suggests that increasing amounts of viscous flow control the chip-removal process. Moreover, viscous flow and crystallization can occur during the machining of the bulk metallic glass, even under the high temperature gradient and strain rate. High cutting speed significantly reduced the forces for BMG machining due to thermal softening. However, in intermittent cutting process which is milling, there is no high temperature problem, special burr formations the rollover and the top burr were observed along the slot and achieved good surface roughness, Ra= 0.113 μm, using conventional WC-Co cutting tool. In each method, tests repeated for the conventional materials for comparison purpose. This study concludes the precision machining of BMG is possible with the selection of feasible tools and process parameters for each method.

Steady-state tensile viscous flow forming of bulk metallic glass

2012 ◽  
Vol 536 ◽  
pp. S109-S112
Author(s):  
E. Soinila ◽  
S. Bossuyt ◽  
H. Hänninen
Keyword(s):  
Steady State ◽  
Metallic Glass ◽  
Viscous Flow ◽  
Bulk Metallic Glass ◽  
Flow Forming

Experimental Studies and Molecular Dynamics Simulations of the Sliding Contact of Metallic Glass

2000 ◽  
Vol 644 ◽  
Author(s):  
Xi-Yong Fu ◽  
Michael L. Falk ◽  
David A. Rigney
Keyword(s):  
Molecular Dynamics ◽  
Metallic Glass ◽  
Molecular Dynamics Simulations ◽  
Bulk Metallic Glass ◽  
Amorphous Material ◽  
Experimental Studies ◽  
Sliding Contact ◽  
Atomic Scale ◽  
Sliding Interface ◽  
Dynamics Simulations

AbstractTribological properties of bulk metallic glass Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 were studied experimentally using a pin/disk geometry without lubrication. Experimental observations were compared with 2D molecular dynamics simulations of amorphous material in sliding contact. The friction coefficient and the wear rate of bulk metallic glass (BMG) depend on normal load and test environment. The sliding of annealed BMG re-amorphizes devitrified material. A mechanically mixed layer is generated during sliding; this layer has enhanced oxygen content if the sliding is in air. The MD simulations show that atomic scale mixing occurs across the sliding interface. The growth kinetics of the mixing process scales with the square root of time. In the simulations, a low density region is generated near the sliding interface; it corresponds spatially to the softer layer detected in experiments. Subsurface displacement profiles produced by sliding and by simulation are very similar and are consistent with the flow patterns expected from a simple Navier-Stokes analysis when the stress state involves both compression and shear.

scholarly journals Plane-Strain Fracture Toughness in Cu-Zr-Ag-Al Bulk Metallic Glass

2008 ◽  
Vol 72 (9) ◽  
pp. 644-647 ◽  
Author(s):  
Yuuki Sakamoto ◽  
Hitoo Tokunaga ◽  
Kazutaka Fujita ◽  
Wei Zhang ◽  
Hisamichi Kimura ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Metallic Glass ◽  
Plane Strain ◽  
Bulk Metallic Glass ◽  
Plane Strain Fracture Toughness ◽  
Strain Fracture

Investigation of bulk metallic glass structure by means of electron irradiation

2009 ◽  
Vol 17 (4) ◽  
pp. 246-248 ◽  
Author(s):  
Yuri Petrusenko ◽  
Alexander Bakai ◽  
Valeriy Borysenko ◽  
Aleksandr Astakhov ◽  
Dmitro Barankov
Keyword(s):  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Electron Irradiation ◽  
Glass Structure
Sign in / Sign up

Export Citation Format

Share Document