(1. 上海市特種設備監(jiān)督檢驗技術研究院，上海 200062； 2. 南京航空航天大學 材料科學與技術學院，南京 211106)
摘 要: 在TC4鈦合金基板表層開槽并預植入塑性的金屬Cu粉體，采用攪拌摩擦加工工藝，利用Cu粉體與攪拌區(qū)鈦基熱塑性組織的反應擴散行為、β-Ti相穩(wěn)定元素Cu對攪拌區(qū)α+β雙相鈦組織α/β相變行為的影響，在優(yōu)化的加工工藝參數(shù)下制備TC4鈦合金表面Ti-Cu合金化改性層，獲得攪拌區(qū)內富β-Ti相區(qū)結構，基于Ti、Cu的二元反應擴散和固溶-析出等行為，生成了Ti2Cu等Ti-Cu中間相，通過改變TC4基板表層的成分組成和物相結構，實現(xiàn)在普通TC4鈦合金表層具有一定的阻燃性能。采用激光點燒蝕法對Ti-Cu改性層耐燒蝕性能進行評價，進而揭示改性層的阻燃機理：通過調控鈦基體表層的α/β兩相比例以提高攪拌摩擦加工冷卻過程后的攪拌區(qū)β-Ti相占比，通過添加阻燃合金元素Cu在改性層內生成Ti-Cu中間相及Ti-Cu合金化層區(qū)。
關鍵字: 攪拌摩擦加工；鈦合金；阻燃機理；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
