(合肥工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院，合肥 230009)
摘 要: 基于高壓扭轉(zhuǎn)工藝，采用XRD、TEM、HRTEM等方法研究不同扭轉(zhuǎn)圈數(shù)(1圈、2圈和5圈)對Al-Zn-Mg-Cu合金第二相的影響。結(jié)果表明：室溫條件下，高壓扭轉(zhuǎn)變形過程中，MgZn2相發(fā)生了回溶現(xiàn)象；由于基體中大量的針狀半共格第二相轉(zhuǎn)變?yōu)榉€(wěn)定的塊狀非共格第二相，界面錯配度增大，比界面能增大，熱力學(xué)的平衡關(guān)系為MgZn2相回溶提供驅(qū)動力。塑性變形產(chǎn)生了大量的位錯切過MgZn2相，引起了MgZn2相的破碎，并提高了Zn原子和Mg原子溶入基體的擴(kuò)散系數(shù)，促使MgZn2相回溶至Al基體中。
關(guān)鍵字: Al-Zn-Mg-Cu合金；高壓扭轉(zhuǎn)；MgZn2相；回溶；位錯
（School of materials science and engineering, Hefei University of Technology, Hefei 23009, China）
Abstract:The effects of different torsional number (1, 2 and 5) on the second phase of Al-Zn-Mg-Cu alloy were studied by means of XRD, TEM and HRTEM based on the high-pressure torsional process. The results show that, under the condition of room temperature and high pressure torsion deformation process, the MgZn2 phase dissolving phenomenon happens; because a large number of acicular half coherent second phase in the matrix into the second phase, the stable block incoherent interface mismatch degree increases, then the thermodynamic equilibrium provides driving force for back-solution of MgZn2 phase. The MgZn2 phase is cut by a lot of dislocation generated by plastic deformation, causing the MgZn2 phase broking, and improve the diffusion coefficient of zinc and Mg atoms into the matrix, prompting MgZn2 phase back into the solution, then into the Al substrate.
Key words: Al-Zn-Mg-Cu alloy; high pressure torsion; MgZn2 phase; back-solution; dislocation
