Oxidation Behavior of a Pd 43 Cu 27 Ni 10 P 20 Bulk Metallic Glass and Foam in Dry Air
- PDF / 738,680 Bytes
- 6 Pages / 593.972 x 792 pts Page_size
- 6 Downloads / 253 Views
NTRODUCTION
PRECIOUS-METAL-BASED amorphous alloys, such as Pd40Ni40P20 (Pd3-BMG), have been developed since the past decades.[1,2] One of the important features for this amorphous alloy was its relatively low glasstransition temperature (Tg . 580 K (307 C)) and good thermal stability (Tx . 660 K (387 C)), which provided a large supercooled liquid region (DTx = Tx Tg) of 80 K (80 C). It was reported that, upon relaxation at a temperature near Tg, this ternary alloy could be easily deformed with an excellent superplasticity of 1260 pct, which made it possible to form complex shapes for industrial applications.[3] Most recently, the quaternary version of this family, the Pd-Cu-Ni-P glassy alloy, has been extensively studied, and the results indicated that the critical cooling rates to retain the glassy structure were significantly lower than those of the ternary alloy.[4–6] In addition, it was also found that the quaternary amorphous alloy containing certain amounts of porosity (i.e., metallic glass foam) exhibited interesting mechanical properties. W. KAI, Professor, and I.F. REN, Graduate Student, are with the Institute of Materials Engineering, National Taiwan Ocean University, Keelung, 20224, Taiwan, Republic of China. Contact e-mail: [email protected] B. BARNARD, Graduate Student, and P.K. LIAW, Professor, are with the Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996. M.D. DEMETRIOU, Senior Research Fellow, and W.L. JOHNSON, Professor, are with the Department of Materials Science, Keck Laboratory, California Institute of Technology, Pasadena, CA 91125. This article is based on a presentation given in the symposium ‘‘Bulk Metallic Glasses VI,’’ which occurred during the TMS Annual Meeting, February 15–19, 2009, in San Francisco, CA, under the auspices of TMS, the TMS Structural Materials Division, TMS/ASM: Mechanical Behavior of Materials Committee. Article published online May 13, 2010 1720—VOLUME 41A, JULY 2010
For example, in the porosity range of 36 to 70 pct, Pd42.5Cu30Ni7.5P20 and Pd43Cu27Ni10P20 foams exhibited strengths in the range of 100 to 600 MPa, elastic moduli in the range of 6 to 32 MPa, and plastic deformation up to 20 to 30 pct strain.[6–8] Nevertheless, the use of Pd4-BMG and its foam in practical applications at higher temperatures requires knowledge of its degradation behavior during oxidation. Thus, it is of interest to investigate the oxidation behavior of the Pd4-BMG and its foamy material in this study. II.
EXPERIMENTAL
The starting materials contained high purity of elemental turnings (at least 99.99 vol. pct pure). A Pd43Cu27Ni10P20 amorphous disk 12 mm in diameter and 4 mm in length (Pd4-BMG) was prepared by injection casting. Another porous Pd43Cu27Ni10P20 disk containing about 45 pct porosity (Pd4-AF), having the same size of Pd4-BMG, was prepared by thermoplastic expansion of entrained gas bubbles.[9] The average composition of the two samples done by the X-ray wavelength-dispersive spectroscopy is 42.1 pct Pd, 25.9 pct Cu, 10.8 p
Data Loading...
