(1. 上海市特种设备监督检验技术研究院，上海 200062； 2. 南京航空航天大学 材料科学与技术学院，南京 211106)
摘 要: 在TC4钛合金基板表层开槽并预植入塑性的金属Cu粉体，采用搅拌摩擦加工工艺，利用Cu粉体与搅拌区钛基热塑性组织的反应扩散行为、β-Ti相稳定元素Cu对搅拌区α+β双相钛组织α/β相变行为的影响，在优化的加工工艺参数下制备TC4钛合金表面Ti-Cu合金化改性层，获得搅拌区内富β-Ti相区结构，基于Ti、Cu的二元反应扩散和固溶-析出等行为，生成了Ti2Cu等Ti-Cu中间相，通过改变TC4基板表层的成分组成和物相结构，实现在普通TC4钛合金表层具有一定的阻燃性能。采用激光点烧蚀法对Ti-Cu改性层耐烧蚀性能进行评价，进而揭示改性层的阻燃机理：通过调控钛基体表层的α/β两相比例以提高搅拌摩擦加工冷却过程后的搅拌区β-Ti相占比，通过添加阻燃合金元素Cu在改性层内生成Ti-Cu中间相及Ti-Cu合金化层区。
关键字: 搅拌摩擦加工；钛合金；阻燃机理；表面改性；合金化
（1. Shanghai Institute of Special Equipment Inspection and Technical Research, Shanghai 200333, China; 2. College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China）
Abstract:The common titanium alloys are prone to spontaneous combustion under a certain service condition of high temperature. The rapid spread of titanium-fire will damage the titanium matrix component. The problem can be effectively solved by the preparation of flame-retardant modified layer on the surface of common titanium alloy. The plastic metal Cu powder was pre-implanted in the grooving prepared in the surface layer on the Ti6Al4V alloy substrate. The friction stir processing was utilized to produce the Ti-Cu alloying modified layer on the surface of Ti6Al4V substrate. The thermal reaction diffusion behavior between the thermoplastic Ti matrix and Cu powder in stir nugget zone benefits to the formation of alloying layer. Meanwhile, β-Ti phase stabilization element of Cu favored for the α-Ti/β-Ti phase proportion modification, aiming to produce more β-Ti phase after the α-Ti/β-Ti transformation during the processing. After the process optimization, the surface modification layer is formed with the β-Ti phase rich zone. The intermetallic phase of Ti2Cu and other Ti-Cu intermediate phases are formed based on the Ti/Cu reaction diffusion and solid solution and precipitation behaviors. The flame-retardant property of the common Ti6Al4V alloy with the modified layer is obtained. The flame-retardant property is evaluated by laser ablation method. Moreover, the flame-retardant mechanism is elucidated in detail. The modification of α/β phase proportion contributes to the increment of β-Ti phase proportion after the friction stir processing cooling procedure. The formation of Ti-Cu intermediate phases and Ti-Cu alloying zone in the modified layer is conducted by adding flame-retardant alloying element of Cu.
Key words: friction stir processing; titanium alloy; flame-retardant mechanism; surface modification; alloying
