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黄广号,李欣,尹冬弟,陆嘉伟,周浩,权高峰.挤压参数和Y含量对Mg-Y合金棒材显微组织及拉-压变形行为的影响[J].稀有金属材料与工程(英文),2018,47(9):2861~2868.[Huang guanghao,Li xin,Yin dongdi,Lu jiawei,Zhou hao and Quan gaofeng.Effect of extrusion parameters and Y content on the microstructure and tension-compression deformation behavior of extruded Mg-Y alloy bars[J].Rare Metal Materials and Engineering,2018,47(9):2861~2868.]
Effect of extrusion parameters and Y content on the microstructure and tension-compression deformation behavior of extruded Mg-Y alloy bars
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Received:November 14, 2016  Revised:March 27, 2017
DOI:
Key words: magnesium-yttrium alloy, extrusion parameters, tension-compression asymmetry, microstructure, mechanical properties.
Foundation item:国家自然科学基金(青年项目)(Nos. 51401172, 51601003)、四川省科技计划(No. 2015HH0012),中央高校基本科研业务费专项资金(No. 2682016CX073)。
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Huang guanghao,Li xin,Yin dongdi,Lu jiawei,Zhou hao and Quan gaofeng  
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Abstract:
      Optical microscope(OM), electron back scattering diffraction(EBSD) and uniaxial tension and compression tests were carried out to investigate the effect of Y content (1,5 wt.%), extrusion temperature(ET) and extrusion ratio(ER) on the microstructure and tension-compression deformation behavior of extruded Mg-Y alloy bars. Results show that the grain change from typical bimodal structure to small ,homogeneous and fully dynamic recrystallized grains with increasing Y content from 1% to 5%(ET=300℃, ER=9). The average grain size of cross section (ED plane) and longitudinal section (TD plane) of two alloy bars are close and approximately 14.1±1.9μm~16.5±1.6μm. As a result of dramatically weakened basal plane fiber texture and decreasing texture intensity (~53%), the room temperature tensile yield strength (TYS) decreases from 173±3MPa to 125±6MPa while fracture strain remarkably raises from 11.0±2.1% to 31.0±1.2%. Furthermore, the tension-compression asymmetry changes from common (CYS/TYS=0.8) to inverse (CYS/TYS=1.10) with increasing of Y content. With the increasing extrusion ratio from 9 to 32 (ET=300℃),the TYS of Mg-1Y alloy bars drastically increases to 242±1MPa (~40%), which may be closely related to fully dynamic recrystallization, finer grain size (~10.1±1.4μm) and obviously weakened basal plane fiber texture (~75%). The increasing extrusion temperature (300~400℃) has little effect on grain size and tension mechanical properties of Mg-1Y alloy bars (ER=32) while compression yield strength (CYS) raises to 236±9MPa (~15%), the value of CYS/TYS changes from 0.85 to 1.02 which means alloy exhibit tension-compression symmetry. Y content has an obvious influence on the deformation behavior of extruded Mg-Y alloy bars. All of the extruded Mg-1Y alloy bars show sigmoid compression stress-strain curve while no similar phenomenon in Mg-5Y alloy bar is observed. Observation of microstructure after compression suggests that this phenomenon is closely related to twining dominant deformation mechanism.