**4. Conclusions**

In summary, our observations revealed that wear resistance behaviors under the dry and the 3.5% NaCl solution conditions can be improved by imparting high structural heterogeneity to Zr54.46Al9.9Ni4.95Cu29.7Pd0.99 BMG using the HRRF method. Under the dry condition, it is obvious that BMGs with different levels of structural heterogeneity showed significantly different wear resistance behaviors. The treated BMG exhibited a wear rate of ~14.7 <sup>×</sup> <sup>10</sup>−<sup>6</sup> mm<sup>3</sup> ·N−1m−<sup>1</sup> which is superior to the ~22.1 <sup>×</sup> <sup>10</sup>−<sup>6</sup> mm<sup>3</sup> ·N−1m−<sup>1</sup> wear rate of the as-cast BMG. Moreover, the predominant wear mechanism of all BMGs under dry-sliding conditions is characterized as abrasive and oxidation wear. Additionally, under the 3.5% NaCl solution condition, the main wear mechanisms are abrasive wear, slight corrosion wear, and adhesive wear. Due to the lubrication and cooling from the solution, although the wear rate of BMGs exhibits much lower levels than those of the dry-friction condition, the wear rate of treated BMGs (~3 <sup>×</sup> <sup>10</sup>−<sup>6</sup> mm<sup>3</sup> ·N−1m−<sup>1</sup> ) was also below the as-cast samples (~4.5 <sup>×</sup> <sup>10</sup>−<sup>6</sup> mm<sup>3</sup> ·N−1m−<sup>1</sup> ). Hence, the combination of improved wear resistance of BMGs both in dry and 3.5% NaCl solution conditions can be achieved. On one hand, the number of oxide layers generated on the worn surface of the treated sample were less than those of the as-cast sample. On the other hand, the higher inhomogeneous structure possesses higher ductility. It can effectively avoid the appearance of delamination, peeling, and cracks on the worn surface. This research provides an unprecedented perspective on BMGs, with easy implementation and celerity to improve wear resistance. We believe our approach presents a guide for the future development of BMGs.

**Author Contributions:** Data curation, Y.M.; Formal analysis, Y.M. and F.Z.; Investigation, Y.M.; Methodology, Y.M.; Resources, F.Z.; Writing—original draft, Y.M. and M.L.; Writing—review & editing, Y.M. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Acknowledgments:** The authors thank Xianping Wang and Yan Jiang at Chinese Academy of Sciences for the Nanoindentation test.

**Conflicts of Interest:** The authors declare no conflict of interest.
