*Article* **Friction and Wear Behavior of an Ag–Mo Co-Implanted GH4169 Alloy via Ion-Beam-Assisted Bombardment**

#### **Jiajun Zhu \*, Meng Xu, Wulin Yang, Deyi Li, Lingping Zhou and Licai Fu \***

College of Materials Science and Engineering, Hunan University, Changsha 410082, China; xumeng@hnu.edu.cn (M.X.); hnuywl@hnu.edu.cn (W.Y.); lideyi@hnu.edu.cn (D.L.); lpzhou@hnu.edu.cn (L.Z.) **\*** Correspondence: tft@hnu.edu.cn (J.Z.); lfu@hnu.edu.cn (L.F.); Tel./Fax: +86-731-8882-2663 (J.Z. & L.F.)

Academic Editors: Braham Prakash and Jens Hardell Received: 12 September 2017; Accepted: 2 November 2017; Published: 6 November 2017

**Abstract:** Ag, Mo, and Ag–Mo were respectively implanted into GH4169 alloy substrates without heating via ion-beam-assisted bombardment technology (IBAB). In addition, the wear performance under low sliding speed and applied load were researched at room temperature (RT). A small amount silver molybdate phase could be detected on the surface of the co-implanted GH4169 alloy bombarded by a high-energy ion beam. The average friction coefficients under the steady wear state had almost no change at all. Compared with the un-implanted GH4169 alloys, the wear rate of the GH4169 alloys with co-implantation of Ag and Mo was reduced by 75%. A large amount of the silver molybdate phase could be generated due to the tribo-reaction on the worn surface during sliding. It benefits the formation of continuous oxide layers as lubrication and protected layers, leading to the change in the predominant wear mechanism from abrasion and adhesion wear to oxidation wear.

**Keywords:** GH4169 alloy; Ag–Mo co-implantation; ion-beam-assisted bombardment technology (IBAB); wear mechanism
