Formation, Thermal Stability and Mechanical Properties of Cu-Zr-Al Bulk Glassy Alloys

Abstract

New Cu-based bulk glassy alloys with large supercooled liquid region and high mechanical strength were found to be formed in Cu-Zr-Al ternary system. The large supercooled liquid region exceeding 70 K was obtained in the composition range of 40 at%Zr at 2.5 at%Al, 37.5%Zr to 47.5%Zr at 5%Al and 42.5%Zr at 7.5%Al. The largest ∆T x was 74 K for Cu 55 Zr 40 Al 5 and Cu 50 Zr 42.5 Al 7.5 alloys and the highest T g /T l was 0.62 for the former alloy. The alloys with large ∆T x values above 70 K were formed into a bulk glassy rod form with diameters up to 3 mm by copper mold casting and the glassy alloy rods exhibit high compressive strength of 1885 to 2210 MPa and Young's modulus of 102 to 115 GPa combined with elastic elongation of 1.60 to 1.95% and plastic elongation of 0 to 0.4%. The addition of 2.5 to 7.5%Al to Cu-Zr alloys was very effective for the increase in glass-forming ability as well as the stabilization of supercooled liquid. The effectiveness can be interpreted on the basis of the concept of the formation of the unique glassy structure in special multi-component alloys with the three empirical component rules.

Unusual Glass-Forming Ability of Bulk Amorphous Alloys Based on Ordinary Metal Copper

“…Moreover, the 12 mm (S2) and 14 mm (S3) samples, even though , from which it can be seen that the critical casting diameter of the matrix alloy is only 3 mm, in agreement with the report in Ref. [18].…”

“…The discovery of these binary BMGs strongly suggests that even higher GFA may be achievable in Cubased alloys by appropriately introducing additional alloying elements. As a matter of fact, Inoue et al reported earlier [18] that the critical casting thickness of certain ternary Cu-based alloys in a Cu-Zr-Al system is 3 mm. Following the ''confusion principle'' proposed by Greer [19], we further examined the effects of other alloying elements on the GFA of a preselected ternary alloy Cu 46 Zr 47 Al 7 (''matrix alloy'' in the following context).…”

Mechanical spectroscopy study of the Cu36Zr59Al5 and Cu54Zr40Al6 amorphous alloys

“…Next, the Cu 36 Zr 59 Al 5 sample was melted again in a furnace (Discovery Plasma: EDG) and the bulk metallic glasses were obtained by the push-pull skull casting technique. The Cu 54 Zr 40 Al 6 sample, provided by Institute of Materials Research at Tohoku University, was melted in a quartz nozzle with a high-frequency induction furnace and cast into a copper mold 21 . The amorphous nature of the samples was verified by X-ray diffraction (XRD), thermal properties of the alloys were characterized by differential scanning calorimetry (DSC) at a heating rate of 40 K/min and the anelastic behavior was characterized by mechanical spectroscopy, using two experimental apparatus: a Kê-type inverted torsion pendulum and an acoustic elastomer system, operating in the Hz and kHz bandwidths respectively.…”

Formation and Mechanical Properties of New Cu-Rich Cu-Zr-Al-Ag Glassy Alloys with High Glass-Forming Ability

“…Therefore, a Cu-rich alloy with high GFA may be obtained in the other composition region in the quaternary alloy system. It has been also demonstrated that the Zr-Cu-Al alloys possess high GFA in the Cu-rich 9) and Zr-rich 11) compositions which are closed to each eutectic point. This article aims to examine the thermal stability, melting behavior and GFA of Cu-rich Cu-Zr-Al-Ag glassy alloys with lower Ag concentrations, to develop new BGAs with high GFA and lower cost.…”

“…In addition, the Cu-rich BGAs can be expected to exhibit higher mechanical strength and higher thermal stability than those of the Zr-rich alloys. [8][9][10] We have reported that the high GFA of the Zr-Cu-Al-Ag alloys is attributed to the eutectic composition, at which solidification occurs via homogeneous nucleation and limited growth rate of the nuclei. 7) It is also known that the multicomponent alloy systems have several deep eutectic points.…”