形變熱處理對Cu-11Zn-0.5Cr合金時效組織和性能的影響

形變熱處理對Cu-11Zn-0.5Cr合金時效組織和性能的影響Effects of thermo-mechanical treatment on microstructure and properties of Cu-11Zn-0.5Cr alloy

采用光學顯微鏡(OM)和透射電鏡(TEM)觀察和分析形變熱處理對Cu-11Zn-0.5Cr合金顯微組織的影響，并測定不同時效工藝合金的力學性能和電學性能。結果表明：合金最佳形變熱處理工藝為熱擠壓-在線水淬-18%冷拉-(450 ℃，4 h)時效，經(jīng)此最佳形變熱處理工藝處理后其硬度、拉伸強度和相對電導率可分別達到128HB、385MPa和41.72%IACS。合金性能主要受時效過程中的時效析出過程和回復-再結晶過程控制。在時效過程中，基體內(nèi)溶質(zhì)原子析出形成細小彌散第二相造成析出強化，且第二相對電子的散射作用較溶質(zhì)原子的弱，使得合金強度和電導率均增大。回復與再結晶使結構中的變形畸變及缺陷消除，使得合金強度減小而電導率增大。

The effect of thermo-mechanical treatment on the microstructure of Cu-11Zn-0.5Cr alloy was investigated by optical microscopy(OM) and transmission electronic microscopy(TEM). The mechanical and electrical properties of Cu-Zn-Cr alloy after different aging treatment were tested. The results show that the optimum thermo-mechanical treatment of Cu-11Zn-0.5Cr alloy is hot extrusion-quenching on line-18% cold drawing-(450 ℃, 4 h) aging. Under the condition, the hardness, the tensile strength and the relative conductivity of 128 HB, 385 MPa and 41.72 %IACS, respectively, can be obtained. The analyzation of the microstructure shows that the mechanical and electrical properties of the alloy are determined by the precipitation and recovery-recrystallization during the aging process. During aging, fine dispersed secondary phases formed by the precipitation of solute atoms in matrix would cause precipitation strengthening, and the secondary phases possess weaker scattering effect on electrons than that of solute atoms, which can enhance the strength and conductivity of the alloy. Besides, deformation distortion and defects in structure are eliminated during the process of recovery and recrystallization, which reduces the strength but enhances the conductivity of the alloy.

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