Shangmou Yang

Members of the RIED Loughborough attended the THERMEC 2023 Conference in Vienna, Austria, a very prestigious bi-annual International Conference on “PROCESSING & MANUFACTURING OF ADVANCED MATERIALS: Processing, Fabrication, Properties, Applications”

The work presented was on the biodegradable and bioresorbable materials for medical devices and scaffolds based on Ca-Mg-Zn chemistry for bulk metallic glasses. PhD researcher Shangmou Yang and supervisors Profs Paul Conway and Carmen Torres presented and defended the paper entitled “Can multifunctionality of bioresorbable BMGs be tuned by controlling crystallinity?” during the session ‘Metallic Glasses 3’ chaired by one of them most eminent and internationally respected experts in bulk metallic glasses, Prof Jürgen Eckert, from Montanuniversität Leoben & Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Leoben (Austria).

^{Shangmou presenting at THERMEC 2023}

It was Shangmou’s first international experience presenting his work; he was well prepared and did a very good job in front of scientists from all over the world who are also working on that alloy system. This work is co-sponsored by Alloyed Ltd, the Wolfson School of Mechanical, Electrical and Mechanical Engineering and EPSRC Programme Grant ‘RIED’.

^{Shangmou happy (and relieved!) after his presentation}

And to make it even more special…

The RIED-Wien local team came to support us and boost our mood!

We met with Dr Vincent McKenna, RIED alumnus, who now resides in Vienna. It was a fabulous occasion, and we spent a lovely time with him there, celebrating how well he is doing in the city he now calls home. We are already looking forward to meeting him again (here in the UK or in Wien!)

^{Shangmou, Vincent, Carmen and Paul at the Belvedere Palace gardens, in Vienna}

As published in Key Engineering Materials Volume 967

Ca-Mg-Zn bulk metallic glasses (BMGs) are promising biomaterials for orthopaedic applications because when they get reabsorbed, a retrieval surgery is not needed. In this study, Ca-Mg-Zn metallic glasses with different compositions, Ca_56.02Mg_20.26Zn_23.72 and Zn_50.72Mg_23.44Ca_25.84, were fabricated by induction melting followed by copper mould casting. Their degree of crystallinity was modified by annealing, obtaining exemplar specimens of fully amorphous, partially amorphous (i.e., a BMG composite (BMGC)) and fully crystalline alloys. The microstructure, thermodynamic and corrosion performance of these alloys were evaluated as well as their electrochemical behaviour. The results of polarisation tests demonstrate that the corrosion resistance of the Zn-rich alloy is markedly better than the Ca-rich BMG. Corrosion rates of these Ca-and Zn-rich alloys with different degrees of crystallinity illustrate that the corrosion behaviours of alloys strongly depend on their microstructure, which shows a positive correlation between the corrosion current density and the crystallised volume fraction of the alloy. This study aims to shed light on the impact of the amorphicity-to-crystallinity ratio on the multifunctional properties of BMGs/BMGCs, and to assess how feasible it is to fine-tune those properties by controlling the percentage of crystallinity.

Shangmou Yang, Carmen Torres-Sanchez, Benoit Ter-Ovanessian, Paul P Conway

Published in the Journal of Alloys and Compounds, Volume 1010, 5 January 2025, 178081

Abstract

Bulk metallic glasses (BMGs) possess higher strength than crystalline alloys because crack propagation is halted through an amorphous structure without grain boundaries or crystal defects. Nanoinclusions can further enhance mechanical properties. Here we investigate how the formation of nanocrystals into a Ti_41.2Zr_10.6Cu_39.1Pd_9.1 BMG matrix via controlled annealing that leads to devitrification of the bulk microstructure, as well as chemical changes to the surface oxide layer, affects mechanical and biological performance. The BMG nanocrystalline composite (BMGC, 12.8 % crystallinity produced via annealing at 415 °C for 5 min, based on crystallisation kinetics studies) was compared to the fully amorphous BMG and the fully crystalline counterpart (annealed at 415 °C and 60 min). BMGC fracture strength (1374.6 MPa) was higher than that of the amorphous BMG (1303.1 MPa) and the fully crystalline specimen (644.4 MPa). Young’s moduli correlated negatively with the degree of crystallisation (78.3–66.2 GPa). The results from in vitro tests on MC3T3-E1 illustrate that the surface chemistry plays a crucial role enhancing osteoblastogenesis: the presence of Zr oxides, wettable surfaces and large values of polar component of Surface Free Energy due to the nanocrystals, and a thinner oxide layer with low concentrations of Cu_xO, positioned BMGC as the preferred substrate. Tailoring amorphicity-to-crystallinity ratio in a Ti-Zr-Cu-Pd BMG is a route to create multifunctional substrates.