Abstract
The aim of the paper was investigation crack initiation and fracture features developed during compression of Fe-based bulk metallic glass (BMG). These Fe-based BMG has received great attention as a new class of structural material due to an excellent properties (e.g. high strength and high elasticity) and low costs. However, the poor ductility and brittle fracture exhibited in BMGs limit their structural application. At room temperature, BMGs fails catastrophically without appreciable plastic deformation under tension and only very limited plastic deformation is observed under compression or bending. Hence a well understanding of the crack initiation and fracture morphology of Fe-based BMGs after compression is of much importance for designing high performance BMGs. The raw materials used in this experiment for the production of BMGs were pure Fe, Co, Nb metals and nonmetallic elements: Si, B. The Fe–Co–B–Si–Nb alloy was cast as rods with three different diameters. The structure of the investigated BMGs rod is amorphous. The measurement of mechanical properties (Young modulus - E, compressive stress - ?c, elastic strain - ?, unitary elastic strain energy – Uu) were made in compression test. Compression test indicates the rods of Fe-based alloy to exhibit high mechanical strength. The development of crack initiation and fracture morphology after compression of Fe-based BMG were examined with scanning electron microscope (SEM). Fracture morphology of rods has been different on the cross section. Two characteristic features of the compressive fracture morphologies of BMGs were observed. One is the smooth region. Another typical feature of the compressive fracture morphology of BMGs is the vein pattern. The veins on the compressive fracture surface have an obvious direction as result of initial displace of sample along shear bands. This direction follows the direction of the displacement of a material. The formation of veins on the compressive fracture surface is closely related to the shear fracture mechanism. The results of these studies may improve the understanding on the fracture features and mechanisms of BMGs and may provide instructions on future design for ductile BMGs with high resistance for fracture.
Highlights
M etallic glasses (MGs) are poised to be mainstay materials for the 21st century due to the unique physical and chemical properties, which offers a great potential for application in industry, medicine, energy systems, microelectronics, aeronautics and many other fields
Bulk metallic glasses (BMGs) possess superior mechanical properties such as high strength and great elastic strain making them ideal candidates for structural applications
The purpose of the paper was an investigation of the mechanical properties, structure and fracture morphology of the Fe36Co36B19Si5Nb4 bulk metallic glass (BMG) after compression
Summary
M etallic glasses (MGs) are poised to be mainstay materials for the 21st century due to the unique physical and chemical properties, which offers a great potential for application in industry, medicine, energy systems, microelectronics, aeronautics and many other fields. Chen fabricated an amorphous Pd-Cu-Si alloy with a diameter of up to 1 mm that could be considered to be a bulk metallic glass (BMG) [3]. In recent years a great expansion in the number of alloy compositions known to give bulk metallic glasses (BMGs) have occurred. Fe-based bulk metallic glasses have been studied as a novel class of engineering materials, which have a good glass forming ability and soft magnetic properties [6,7]. BMGs exhibit good soft magnetic properties, as well as super-high fracture strength of 3000–4000MPa and ductile strain of 0.002 [6]. Bulk metallic glasses (BMGs) possess superior mechanical properties such as high strength and great elastic strain making them ideal candidates for structural applications. The purpose of the paper was an investigation of the mechanical properties, structure and fracture morphology of the Fe36Co36B19Si5Nb4 bulk metallic glass (BMG) after compression
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