Influence of shot peening on the mechanical properties of bulk amorphous Vitreloy 105

Abstract

The quasi-static and cyclic properties of bulk glassy Zr 52.5 Cu 17.9 Al 10 Ni 14.6 Ti 5 alloy (Vitreloy 105) were investigated under three-point bending conditions for two different shot-peened surface states. Residual stress analysis and nanoindentation measurements revealed the presence of compressive residual stresses and an enhanced hardness in the near surface layer after shot peening. Further investigations of the longitudinal cross-sections of the mechanically tested specimens by optical and scanning electron microscopy showed small cracks propagating along shear bands in the vicinity of the fracture surface. The results are in accordance with the improved plasticity of the shot-peened states under quasi-static loading conditions compared to the as-cast reference state. All mechanical testing was carried out with the aim to find a material's state with improved mechanical properties with a special focus on the improvement of the fatigue lifetime and the endurance limit of Vitreloy 105 bulk metallic glass.

Atomistic modeling of heat treatment processes for tuning the mechanical properties of disordered solids

“…The processing routes often involve mechanical and thermal treatments of disordered alloys that lead to changes in microstructure as well as mechanical and physical properties [3]. It is well realized by now that metallic glasses relax to lower energy states during the aging process and become more brittle, while rejuvenation and improved plasticity can be achieved using a number of experimental techniques, such as shot peening [4], cold rolling [5], high pressure torsion [6], ion irradiation [7], and cryogenic thermal cycling [8,9]. In turn, recent atomistic simulations have shown that periodically loaded disordered materials evolve towards lower energy states at sufficiently small strain amplitudes, whereas the yielding transition and shear localization occur at large amplitudes after a number of transient cycles [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25].…”

Cyclic cryogenic pretreatments influencing the mechanical properties of a bulk glassy Zr‐based alloy

“…Woehler curves for the various Vitreloy 105 material states (sinusoidal load control, f = 50 Hz, R = 0.1) tested under cyclic three‐point bending conditions; data of the as‐cast state was taken from a previous study…”

“…For cryo state C, the fatigue strength was set to the arithmetic medium stress level, at which the number of runout and fractured specimens was expected to be the same. Fatigue data of the as‐cast material were obtained from a previous study . For gaining further information about the mechanical properties and the damage mechanisms of the cryogenically treated Zr‐based BMG, a special setup for impact toughness measurements on small‐scale samples was developed.…”

“…Improving the mechanical properties of bulk metallic glasses (BMGs), especially their plastic deformation capability, has been a major goal of many research groups in the last two decades. Conventional methods to enhance the plasticity, which makes fracture of these BMG specimens more predictable, are given by, eg, shot peening, mechanical imprinting, cold rolling, or introducing crystalline microparticles . While most of these treatments also affect the surface morphology of the material, which is possibly a drawback for specific technical applications, there is a very recent approach to influence the mechanical properties of bulk amorphous alloys by thermal cycling between room temperature and cryogenic temperatures prior to mechanical testing.…”

Changes in the crystallization sequence upon sulfur addition in the Zr52.5Cu17.9Ni14.6Al10Ti5<

“…One of the most used bulk metallic glasses (BMGs) for industrial applications is the Zr-based alloy Zr 52.5 Cu 17.9 Ni 14.6 Al 10 Ti 5 (Vit105). It combines excellent mechanical properties [1][2][3][4][5] with a high glass-forming ability (GFA) [6][7][8], making it easy to process and cast into amorphous parts [9]. Furthermore, it contains no toxic elements, precious metals, or rare-earth metals, making it the perfect candidate for industrial production.…”