Crystallization of CuZrAgAl Bulk Metallic Glass at Various Temperatures and Pressures

Abstract

The Cu₄₃Zr₄₃Ag₇Al₇ alloy was obtained in an amorphous form through inert gas spray forming, followed by separation using a tower cyclone gas separator. The resulting spherical particles were about 11 μm in size. The consolidation of the powder was carried out using two distinct methods. First, Spark Plasma Sintering (SPS) was performed under a pressure of 35 MPa at two temperatures: 750°C and 900°C. Second, the High-Pressure High-Temperature (HPHT) method was applied, utilizing a toroidal-type Bridgman apparatus at about 560°C under a pressure of 7.8 GPa. In both processes, the consolidation duration was one minute. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HRTEM) analyses revealed distinct differences in the crystallization behavior of the alloy. SPS processing led to complete crystallization, resulting in the formation of Zr₂Cu, Ag₂Al, and Cu₁₀Zr₇ crystalline phases. In contrast, the HPHT method significantly delayed crystallization, with only nanocrystalline nuclei observed within the amorphous matrix. Additionally, the application of high pressure in the HPHT process resulted in lower porosity and higher hardness compared to the SPS method.