Periodically Laser Patterned FeBSi Amorphous Ribbons: Phase Evolution and Mechanical Behavior

Abstract

Bulk metallic glasses or amorphous alloys, in contrast to crystalline materials, exhibit superior properties, such as high hardness, elastic modulus/limits, and corrosion/wear resistance because of their disordered atomic structure without long-range periodicity. [1][2][3][4] These alloys are attracting increasing attention as potential materials for a range of applications in structural, biomedical, and microelectronic industries. [5][6][7][8][9][10][11] However, the actual utilization of amorphous materials in practical applications is limited due to their near-complete brittleness accompanied with strain softening and shear localization. This limited plasticity of amorphous materials is often attributed to the initiation and propagation of localized regions of extensive plastic deformation known as shear bands. [12][13][14][15] There has been a great thrust toward improving the overall global plasticity of amorphous materials by designing amorphous matrix composites reinforced with crystalline phases. [16][17][18] The amorphous matrix composites can also be formed in situ by controlled thermal processing such that partial devitrification results in precipitation of small crystallites in the amorphous matrix. These reinforced crystalline phases are expected to promote the initiation of shear bands and also hinder the propagation of shear bands, thus enhancing the global plasticity of the amorphous materials. [19][20][21][22][23] Most of the ductility-enhancement methods applied to amorphous materials are focused on designing bulk amorphous matrix composites with reinforced crystalline phases. [24,25] However, the role of surface treatments on the deformation and failures of amorphous materials is not well studied. Recently, significant research interests are attracted toward enhancing the plasticity of the amorphous materials by means of surface engineering methods. Most of the interests were invigorated after the publication of a paper by Zhang et al. regarding plasticity enhancement (plasticity in compression and bending) of amorphous materials by controlling the residual state of stresses on the surface of amorphous materials. [26] The compressive surface stresses were induced in the Zr-based amorphous materials by a shot-peening method. The compressive stresses in the peened surfaces caused more shear bands with smaller shear on each band, thus facilitating general continuing plasticity instead of a premature failure on few dominant shear bands. It was observed that the enhanced plasticity in compression and bending is due to a combination of a reduced likelihood of surface cracking and more uniform deformation induced by high population of pre-existing shear bands. [26] More recently, a controlled surface crystallization of amorphous materials by a surface mechanical attrition treatment (SMAT) has beenThe properties of amorphous alloys are significantly influenced by structural relaxation and partial/full crystallization induced by thermal annealing of the alloy. In this paper, the phase evolution and mech...

Dry Sliding Wear Behavior of Spark Plasma Sintered Fe-Based Bulk Metallic Glass/Graphite Composites

“…The wear testing conditions can also cause structural relaxation and partial devitrification of amorphous alloys due to contact stress (mechanical) and frictional heat (thermal) mechanisms [10,13]. The crystallization products in amorphous alloys most often embrittle the material [16]. The microcracking at the crystal interfaces and removal of hard particles further deteriorate the wear performance.…”