Ultra-high strength above 5000 MPa and soft magnetic properties of Co-Fe-Ta-B bulk glassy alloys

A. Inoue, B. L. Shen, H. Koshiba, H. Kato, A. R. Yavari

Research output: Contribution to journalArticlepeer-review

221 Citations (Scopus)


Glassy Co43Fe20Ta5.5B31.5 alloy rods with glass transition temperature of 910 K, followed by a large supercooled liquid region of 72 K were produced in the diameter range up to 2 mm by copper mold casting. The glassy alloy rods exhibit ultra-high fracture strength of 5185 MPa, high Young's modulus of 268 GPa, high specific strength of 6.0×105 N m kg-1 and high specific Young's modulus of 31×106 N m kg-1. The fracture strength, specific strength and specific Young's modulus obtained by compression test are higher than all previous values reported for any crystalline and glassy alloys. The ultra-high strength of over 5000 MPa persists in the temperature range up to 698 K. The fracture occurred on one major shear band which was declined by 44° to the stress axis implying the slight deviation from the maximum shear stress plane. Excellent formability is manifested by large tensile elongation of 1400% and large reduction ratio in thickness above 90% in the supercooled liquid region. The ultra-high strength alloy exhibits simultaneously good soft magnetic properties: low coercivity of 0.25 A/m and an extremely high permeability of 550,000. The novel alloy is promising as a new ultra-high strength material with good deformability and soft magnetic properties.

Original languageEnglish
Pages (from-to)1631-1637
Number of pages7
JournalActa Materialia
Issue number6
Publication statusPublished - 2004 Apr 5


  • Bulk metallic glasses
  • High temperature deformation
  • Magnetic properties
  • Shear bands
  • Superplasticity

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys


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