Enhanced tensile strength and ductility of bulk metallic glasses Zr52.5Cu17.9Al10Ni14.6Ti5 via high-pressure torsion

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2021-01, Vol.803 (C), p.140485, Article 140485
• Main Authors: Ren, Zhi Qiang, Churakova, A.A., Wang, Xiang, Goel, Sunkulp, Liu, Si Nan, You, Ze Sheng, Liu, Ying, Lan, Si, Gunderov, D.V., Wang, Jing Tao, Valiev, R.Z.
• Format: Article
• Language: English
• Subjects: Amorphous materials; Amorphous-crystalline composites; Chemical precipitation; Crystallites; Ductility; Ductilization window; Free volume; Inter-crystallite spacing; Metallic glasses; Nanocrystals; Precipitates; Room temperature; Strength; Tensile ductility; Tensile strength
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2020.140485

Zr52.5Cu17.9Al10Ni14.6Ti5 (Vit105) Bulk metallic glass is processed by High-Pressure Torsion up to 30 rotations at room temperature, showing simultaneous enhancement of both strength (2023 MPa) and ductility (0.45%). Nano-crystal precipitates with an average size of 45 nm inside the amorphous matrix are observed after 30 turns HPT. Free volume increases from ~0.9030 Å3 (as cast) to ~0.9275Å3 after 30 turn HPT alloy with 2.83% (by volume) of nanocrystal precipitates. Strengthening due to precipitation after 30 turns HPT comply with the phase mixture model. The synergetic effect of free volume and nanocrystal precipitation on the ductility of amorphous-crystallite composite is quantitatively approached through modelling. By implementing the model, a ductilization window between bottom limit and top limit of the inter-crystallite spacing w.r.t the free volume is established, elucidating the necessary conditions required to obtain plasticity in amorphous-crystalline composites. •Both ductility and strength of BMGs are enhanced by HPT processing.•The nanocrystals precipitation during HPT increases the strength.•Free volume increase during HPT enhances ductility and reduces yield stress.•Synergetic effect of free volume and nanocrystals on ductility was observed.•Mechanism based-modelling correctly predict the synergetic effect on ductility.