Super-high strength of over 4000 MPa for Fe-based bulk glassy alloys in [(Fe1-xCox)0.75B0.2Si0.05]96Nb4 system

• Published in: Acta materialia Vol. 52; no. 14; pp. 4093 - 4099
• Main Authors: INOUE, A, SHEN, B. L, CHANG, C. T
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Science 16-08-2004
• Subjects: Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Glasses (including metallic glasses); Materials science; Physics; Specific materials; Differential scanning calorimetry; Hardness test; Property composition relationship; Mechanical strength; Compressive testing; Mechanical properties; Niobium alloys; Amorphous alloy; Differential thermal analysis; XRD; Experimental study; Glass transition temperature; Compression test; Boron alloys; Glass transition; Metallic glasses; Silicon alloys; Rapid solidification; True stress true strain curve; Fractography; Slip markings; Cobalt alloys; Iron base alloys
• ISSN: 1359-6454; 1873-2453
• DOI: 10.1016/j.actamat.2004.05.022

New Fe-based bulk glassy alloys with diameters up to 5 mm were formed in [(Fe(1-x)Co(x))0.75B(0.2)Si(0.05)]96Nb4 system by the copper mold casting method. The substitution of Co for Fe causes an increase in the glass-forming ability (GFA). As the Co content increases, the liquidus temperature (T) decreases, resulting in an increase of reduced glass transition temperature (Tg/Tl) from 0.566 to 0.587. The bulk glassy alloys exhibit super-high fracture strength of 3900-4250 MPa, Young's modulus (E) of 190-210 GPa, elastic strain (epsilon(e)) of 0.02, plastic strain (epsilon(p)) of 0.0025 and Vickers hardness (HH) of 1150-1220. The sigma(f)/E and Hv/3E of these glassy alloys are 0.02, respectively, in agreement with the previous data for a number of bulk glassy alloys. The agreement indicates that these Fe-based bulk glassy alloys have an elastic-plastic deformation mode. The syntheses of high-strength Fe-based bulk glassy alloys with superhigh fracture strength of over 4000 MPa and high glass-forming ability are encouraging for future development of Fe-based bulk glassy alloys as structural materials.