脉冲电流对AZ31B镁合金板材退火过程的影响（英文）
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摘要
通过脉冲电流和热处理炉对AZ31B镁合金板材进行退火处理,并分析脉冲电流对合金显微组织及位错密度演化的影响。结果表明:脉冲电流能增强晶界的迁移,使孪生晶粒球化成等轴晶,从而切割原始粗大晶粒并细化显微组织。该过程能使原始显微组织更加均匀,并消除典型的层片状孪晶。此外,脉冲电流还能增强位错的湮灭。当材料在300°C下脉冲电流辅助退火4 min后,其位错密度甚至低于在400°C的热处理炉中退火3 h且未发生塑性变形的组织。不仅如此,脉冲电流对位错湮灭的促进作用随峰值电流密度的增强及脉冲频率的降低而增强。
The annealing tests heated by pulsed current(PC) or furnace for AZ31B magnesium sheets were carried out, and the effects of PC on the microstructure and dislocation density of the alloy were analyzed. The results show that PC strengthens the migration of boundaries, and then the twin grains, most of which distribute in the coarse grains, "spheroidize" to equiaxed grains,thus separating the coarse grains and refining the microstructure. This process homogenizes the initial microstructure and eliminate the typically lamellar twin grains. Moreover, PC also strengthens the dislocation annihilation. When the specimens were annealed by PC at 300 °C for 4 min, the dislocation density was even lower than that annealed by furnaces at 400 °C for 3 h before deformation.Furthermore, dislocation annihilation is enhanced with the increase of peak current density and the decrease of pulsed frequency.
The annealing tests heated by pulsed current(PC) or furnace for AZ31B magnesium sheets were carried out, and the effects of PC on the microstructure and dislocation density of the alloy were analyzed. The results show that PC strengthens the migration of boundaries, and then the twin grains, most of which distribute in the coarse grains, "spheroidize" to equiaxed grains,thus separating the coarse grains and refining the microstructure. This process homogenizes the initial microstructure and eliminate the typically lamellar twin grains. Moreover, PC also strengthens the dislocation annihilation. When the specimens were annealed by PC at 300 °C for 4 min, the dislocation density was even lower than that annealed by furnaces at 400 °C for 3 h before deformation.Furthermore, dislocation annihilation is enhanced with the increase of peak current density and the decrease of pulsed frequency.
引文
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[13]LI Xiao-pei,LI Xiao-hui,ZHU K S,TANG Guo-yi.A comparative study on the static recrystallization behavior of cold-rolled Mg-3Al-1Zn alloy stimulated by electropulse treatment and conventional heat treatment[J].Metallurgical and Materials Transactions A,2018,49:613-627.
[14]LIU Kai,DONG Xiang-huai,XIE Huan-yang,WU Yun-jian,PENGFang.Influence of pulsed current on deformation mechanism of AZ31B sheets during tension[J].Journal of Alloys and Compounds,2016,676:106-112.
[15]LIU Kai,DONG Xiang-huai,XIE Huan-yang,PENG Fang.Effect of pulsed current on the deformation behavior of AZ31B magnesium alloy[J].Materials Science and Engineering A,2015,623:97-103.
[16]XIE Huan-yang,WANG Qian,PENG Fang,LIU Kai,DONGXiang-huai,WANG Jian-feng.Electroplastic effect in AZ31Bmagnesium alloy sheet through uniaxial tensile tests[J].Transactions of Nonferrous Metals Society of China,2015,25:2686-2692.
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[18]UNGáR T.Microstructural parameters from X-ray diffraction peak broadening[J].Scripta Materialia,2004,51:777-781.
[2]TROITSKII O A.Electroplastic effect in metals[J].Soviet Physics Solid-State,1970,26:28-33.
[3]OKAZAKI K,KAGAWA M,CONRAD H.A study of the electoplastic effect in metals[J].Scripta Metallurgica,1978,12:1063-1068.
[4]OKAZAKI K,KAGAWA M,CONRAD H.An evaluation of the contributions of skin,pinch and heating effects to the electroplastic effect in titanium[J].Materials Science and Engineering A,1980,45:109-116.
[5]CONRAD H.Thermally activated plastic flow of metals and ceramics with an electric field or current[J].Materials Science and Engineering A,2002,322:100-107.
[6]CONRAD H.Electroplasticity in metals and ceramics[J].Materials Science and Engineering A,2000,287:276-287.
[7]ZHU Y H,TO S,LEE W B,LIU X M,JIANG Y B,TANG G Y.Effects of dynamic electropulsing on microstructure and elongation of a Zn-Al alloy[J].Materials Science and Engineering A,2009,501:125-132.
[8]KIM M J,LEE K H,OH K H,CHOI I S,YU H H,HONG S T,HANH N.Electric current-induced annealing during uniaxial tension of aluminum alloy[J].Scripta Materialia,2014,75:58-61.
[9]XU Xiao-feng,ZHAO Yu-guang,MA Bing-dong,ZHANG Ming.Rapid precipitation of T-phase in the 2024 aluminum alloy via cyclic electropulsing treatment[J].Journal of Alloys and Compounds,2014,610:506-510.
[10]XU Xiao-feng,ZHAO Yu-guang,MA Bing-dong,ZHANG Jia-tao,ZHANG Ming.Rapid grain refinement of 2024 Al alloy through recrystallization induced by electropulsing[J].Materials Science and Engineering A,2014,612:223-226.
[11]JEONG H J,KIM M J,PARK J W,YIM C D,KIM J J,KWON O D,MADAKASHIRA P P,HAN H N.Effect of pulsed electric current on dissolution of Mg17Al12 phases in as-extruded AZ91 magnesium alloy[J].Materials Science and Engineering A,2017,684:668-676.
[12]PARK J W,JEONG H J,JIN S W,KIM M J,LEE K Y,KIM J J,HONG S T,HAN H N.Effect of electric current on recrystallization kinetics in interstitial free steel and AZ31 magnesium alloy[J].Materials Characterization,2017,133:70-76.
[13]LI Xiao-pei,LI Xiao-hui,ZHU K S,TANG Guo-yi.A comparative study on the static recrystallization behavior of cold-rolled Mg-3Al-1Zn alloy stimulated by electropulse treatment and conventional heat treatment[J].Metallurgical and Materials Transactions A,2018,49:613-627.
[14]LIU Kai,DONG Xiang-huai,XIE Huan-yang,WU Yun-jian,PENGFang.Influence of pulsed current on deformation mechanism of AZ31B sheets during tension[J].Journal of Alloys and Compounds,2016,676:106-112.
[15]LIU Kai,DONG Xiang-huai,XIE Huan-yang,PENG Fang.Effect of pulsed current on the deformation behavior of AZ31B magnesium alloy[J].Materials Science and Engineering A,2015,623:97-103.
[16]XIE Huan-yang,WANG Qian,PENG Fang,LIU Kai,DONGXiang-huai,WANG Jian-feng.Electroplastic effect in AZ31Bmagnesium alloy sheet through uniaxial tensile tests[J].Transactions of Nonferrous Metals Society of China,2015,25:2686-2692.
[17]UNGAR T,OTT S,SANDERS P G,BORBELY A,WEERTMAN JR.Dislocations,grain size and planar faults in nanostructured copper determined by high resolution X-ray diffraction and a new procedure of peak profile analysis[J].Acta Materialia,1998,46:3693-3699.
[18]UNGáR T.Microstructural parameters from X-ray diffraction peak broadening[J].Scripta Materialia,2004,51:777-781.