Preparation of Ti-Cu Alloying Surface Layer on Ti6Al4V Substrate via Friction Stir Processing for Flame-Retardant Performance

Under a certain condition of high temperature, the common titanium alloys are prone to spontaneous combustion in service. The titanium-fire will rapid spread and damage the titanium matrix component. The problem could be effectively solved by the preparation of flame-retardant modified layer on the surface of common titanium alloy. In the present paper, the plastic metallic Cu powder was implanted into the grooving prepared in the surface layer on the Ti6Al4V alloy substrate. The friction stir processing technology was newly-utilized for producing Ti-Cu alloying modified layer on Ti6Al4V substrate. To obtain the good surface modification layer forming and the beta-Ti phase rich zone in the Ti-Cu alloying layer, the process optimization was conducted. The inter-metallic phase of Ti2Cu and other Ti-Cu intermediate phases were produced in Ti-Cu alloying layer. The flame-retardant performance of common Ti6Al4V alloy with the modified layer was evaluated via laser ablation. Then, the flame-retardant mechanism was elucidated.