Shujie Pang

Synthesis of Fe-Cr-Mo-C-B-P bulk metallic glasses with high corrosion resistance

Bulk metallic glasses with a maximum thickness (tmax) of 1.0–2.7 mm were synthesized in the Fe43Cr16Mo16(C, B, P)25 system over a wide composition range by copper mold casting. They exhibit a large supercooled liquid region (ΔTx) of 40–90 K and a high reduced glass transition temperature (Tg/Tl) of 0.54–0.60, indicating high glass-forming ability (GFA) and high thermal stability of the supercooled liquid. The critical cooling rate for glass formation was evaluated to be of the order of 102 K s−1. The bulk metallic glasses exhibited high corrosion resistance in aggressive HCl solutions. The alloying element P has a beneficial effect on corrosion resistance.

Formation of Bulk Glassy Fe 75– x – y Cr x Mo y C 15 B 10 Alloys and Their Corrosion Behavior

Formation of bulk Fe-based glassy alloys with high corrosion resistance was succeeded in the Fe 7 5 - x - y Cr x Mo y C 1 5 B 1 0 alloy system. A large temperature interval of supercooled liquid region (ΔT x ) of 40-90 K was obtained over a wide composition range for the Fe 7 5 - x - y Cr x Mo y C 1 5 B 1 0 alloys. The Fe 7 5 - x - y Cr x Mo y C 1 5 B 1 0 alloys were prepared in a bulk glassy form with diameters of 1.0-2.5 mm by copper mold casting. The bulk glassy Fe 7 5 - x - y Cr x Mo y C 1 5 B 1 0 alloys exhibited high corrosion resistance in 1 N HCl solution. The glassy alloys containing Cr were spontaneously passivated with a wide passive region before the transpassive dissolution of Cr. The passive current density decreased significantly with an increase of alloying Cr content, indicating that the addition of Cr was effective on enhancing the corrosion resistance. Excess addition of Mo for replacing Fe in the present alloys was detrimental for the corrosion resistance.

Formation, corrosion behavior, and mechanical properties of bulk glassy Zr–Al–Co–Nb alloys

Bulk glassy Zr 5 5 Al 2 0 - x Co 2 5 Nb x (x = 0 to 5 at.%) alloys with critical diameters of 2.5-5 mm and supercooled liquid region of 48-75 K were produced by copper-mold casting. These alloys were spontaneously passivatedin 3 mass% NaCl and 1 N H 2 SO 4 solutions. The addition of Nb to the alloy enhanced the pitting corrosion resistance in the NaCl solution and enabled the open-circuit potential in the H 2 SO 4 solution. Zr- and Al-enriched passive films formed on the bulk glassy Zr-Al-Co-Nb alloys exposed to air and on those immersed in the solutions. The increase in Nb content of the alloys resulted in an increase in Zr and Nb concentrations and a decrease in Al concentration of the passive film. The Vickers hardness, Youngs modulus, compressive fracture strength, fracture strain, and plastic strain of the bulk glassy Zr-Al-Co-Nb alloys were 550, 98 GPa, 2100 MPa, 2.9%, and 0.9%, respectively.

Preparation and Corrosion Resistance of Fe-Cr-Mo-C-B-P Bulk Glassy Alloys

Fe-based bulk metallic glasses with high corrosion resistance were prepared and evaluated. By using copper mold casting, bulk glasses with a thickness up to 2.5 mm were able to be prepared in the Fe-Cr-Mo-C-B-P system. The Fe-Cr-Mo-C-B-P system metallic glasses exhibited a composition range which has a large supercooled liquid region up to 90 K and a highly reduced glass transition temperature reaching 0.6, indicating a high glass-forming ability (GFA) and high thermal stability of the supercooled liquid. They exhibit good corrosion resistance in HCl solutions. Phosphorus has a beneficial effect on corrosion resistance, but a lowered GFA.