金包銅復(fù)合微絲拉拔過程中組織與性能的演變

金包銅復(fù)合微絲拉拔過程中組織與性能的演變Evolution of microstructure and mechanical properties of gold cladding copper micro-wire during drawing

采用旋鍛-拉拔-擴散退火-拉拔方法制備直徑60 μm金包銅復(fù)合微絲，研究拉拔過程中復(fù)合微絲顯微組織、力學(xué)性能和導(dǎo)電率的變化規(guī)律。結(jié)果表明：所制備的微絲表面光潔和金/銅界面結(jié)合狀態(tài)良好，金層平均厚度約為2.0μm，橫斷面金包覆層面積比約為10.5%。在拉拔過程中，當(dāng)真應(yīng)變增大至2.5時，復(fù)合微絲銅芯由退火態(tài)的等軸晶組織逐漸轉(zhuǎn)變?yōu)闂l狀纖維組織，晶內(nèi)小角度晶界數(shù)量明顯增大，微絲的抗拉強度由退火態(tài)的235 MPa增大至最大值451 MPa，而斷后伸長率由退火態(tài)的49.5%降低至1.2%，導(dǎo)電率由100.0%(IACS)下降為98.3%(IACS)；繼續(xù)增大真應(yīng)變至3.5和4.8時，加工過程中產(chǎn)生的變形熱使銅芯發(fā)生動態(tài)回復(fù)和動態(tài)再結(jié)晶，小角度晶界數(shù)量降低，大角度晶界數(shù)量增多；當(dāng)真應(yīng)變?yōu)?.8時，微絲的抗拉強度為439MPa，伸長率上升至3.0%，導(dǎo)電率下降到94.5%(IACS)。

A method of rotary forging-drawing-diffusion annealing-drawing was proposed to produce d0.06 mm gold cladding copper micro-wire. The evolutions of the microstructure, mechanical properties and electrical conductivity of the micro-wire during drawing were studied. The results show that the prepared gold cladding copper micro-wire exhibits the smooth surface, good Au/Cu bonding interface, gold layer with an average thickness of 2.0 μm and cladding ratio of about 10.5%. During drawing, when the true strain increases to 2.5, the microstructure of the copper core changes from equiaxed grains of the annealed wire to fiber grains, and the number of low angle grain boundary increases significantly. The tensile strength of the composite wire increases from 235 MPa of the annealed wire to the maximum of 451 MPa, while the elongation to failure decreases from 49.5% of the annealed wire to 1.2%, and the electrical conductivity decreases from 100.00%(IACS) of the annealed wire to 98.3%(IACS). When the true strain increases to 3.5 and 4.8, the dynamic recovery and dynamic recrystallization occurs in the copper core due to deformation heat generated during drawing, the number of low angle grain boundary reduces while the number of high angle grain boundary increases. At the true strain of 4.8, the tensile strength of the composite wire is 439 MPa, the elongation increases to 3.0% and the electrical conductivity decreases to 94.5%(IACS).

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