Mechanical Properties and Fracture Characteristics of Zr-Based Bulk Metallic Glass Composites Containing Carbon Nanotube
- PDF / 1,259,132 Bytes
- 9 Pages / 612 x 792 pts (letter) Page_size
- 53 Downloads / 217 Views
Mechanical properties and fracture characteristics of Zr-based bulk metallic glass (BMG) composites containing carbon nanotube (CNT) addition were investigated in detail. The interfacial reaction between the added CNTs and the glass matrix causes the formation of some V-shape nicks on the residual CNTs. These nicks have significant effect on the mechanical properties and fracture modes of the BMG composites. The compressive fracture strength increases with increasing the volume fraction of CNT addition at first, and starts to decrease gradually when the volume fraction of CNT addition is more than 5.0%. The fracture modes of the BMG composites also change from typical shear flow deformation behavior to completely embrittling fracture gradually. The V-shape nicks originating from the interfacial reaction are responsible for the decrease of fracture strength and the variation of fracture modes.
I. INTRODUCTION
Recently, considerable scientific and industrial effort has been made to produce bulk metallic glass (BMG) composites as a way to improve further mechanical properties compared to monolithic BMGs. BMGs are also promising matrix materials for producing composites because of their low melting points of around 1000 K and their high resistance against heterogeneous nucleation of crystals.1,2 BMG composites reinforced with metals or ceramics particles3–7 can improve significantly fracture strength and plasticity of Zr-based BMGs. Kato et al.6 have reported that Zr55Al10Ni5Cu30 BMG composites containing up to 17 vol% ZrC particles were produced. The average particle size and interparticle spacing of the ZrC particles are 3 and 4 m, respectively, and neither distinct agglomeration nor segregation of the ZrC particles is seen on the transverse and longitudinal crosssections. The Young’s modulus, compressive strength, and Vickers hardness for the composites increase almost linearly with increasing the volume fraction of ZrC from 0 to 17 vol%. The plastic elongation also increases from nearly zero for 0 vol% to 0.5% at 10 vol%. Conner et al.3 have reported that the compressive strain of BMG composites reinforced by W, WC, Ta, and SiC increases by more than 300% compared with the unreinforced BMG,
II. EXPERIMENTAL
a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2004.0140 1068
and the fracture energy of the tensile samples increases by more than 50%. Kim et al.8 have also reported that carbon-fiber–reinforced BMG composites are prepared successfully by infiltrating liquid Zr–Ti–Cu–Ni–Be into carbon-fiber bundles. The glassy state of the matrix was retained after processing. More recently, Zr-based BMG composites containing carbon nanotubes (CNTs) were also successfully prepared.9–11 Investigation shows that Zr-based BMG composites containing CNTs have strong ultrasonic attenuation and excellent wave absorption ability.10,11 Residual CNTs dispersing in the glass matrix still partially keep their cylindrical graphitic structure and unique multiwalled structure.9,11 However, up to
Data Loading...
