富Ce稀土与超声场对Al-Si合金中富铁相的影响
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摘要
研究了富Ce稀土变质与超声场的协同作用对Al-11.5Si-3.8Cu-2.6Ni-0.5Mg-0.45 Fe合金中富铁相(α-Al_5FeSi)形貌以及尺寸的影响,并进一步研究了两种处理方式下合金高温拉伸性能的变化。采用光学显微镜(OM)、扫描电镜(SEM)对试样微观组织进行观察,通过能谱仪(EDS)、 X射线衍射仪(XRD)进行相分析。结果表明:在富Ce稀土变质与超声场的协同作用下,α-Al_5FeSi相从多边形大块状转变为不规则的小块状;其平均等积圆直径从38.23μm减小到13.8μm;合金的350℃抗拉强度从104.1 MPa增加到116.9 MPa,延伸率从3.2%增大到4.8%。稀土元素在α-Al_5FeSi相界面上的富集改变了界面前沿的熔体结构,对α-Al_5FeSi相的生长有抑制的作用。超声空化作用产生的局部高温高压促进了固液界面溶质富集区溶质的传输和扩散,从而能一定程度地碎化α-Al_5FeSi相,经过稀土变质处理之后,超声处理的碎化效果加大。
The combined effects of Ce-rich rare earths(RE) modification and ultrasonic field on morphology and size of iron-rich phase(α-Al_5FeSi) in Al-11.5 Si-3.8 Cu-2.6 Ni-0.5 Mg-0.45 Fe alloys were investigated and elevated temperature tensile properties of the alloy were analyzed. The microstructure was observed by optical microscope(OM) and scanning electron microscope(SEM). The phase observation and analysis of the alloy were conducted by energy dispersive spectrometer(EDS) and X-ray diffraction(XRD). The results showed that the α-Al_5FeSi phase proceeded by Ce-rich RE modification and ultrasonic field was transformed from the massive polygons to the irregular small lumps. The equal-area-circle diameter of α-Al_5FeSi phase decreased from 38.23 to 13.8 μm. The tensile strength at 350 ℃ of alloy increased from 104.1 to 116.9 MPa, and the elongation increased from 3.2% to 4.8%. The melt structure at the tip of α-Al_5FeSi phase was transformed due to enrichment of rare earth, which hampered the growth of α-Al_5FeSi phase. The spread and diffusion of solute in the solute-rich region at the solid-liquid interface was promoted because of high temperature and pressure generated by ultrasonic cavitation, which could break the α-Al_5FeSi phase to a certain degree. After the modification of rare earth, the fragmentation of the ultrasonic treatment became obvious.
The combined effects of Ce-rich rare earths(RE) modification and ultrasonic field on morphology and size of iron-rich phase(α-Al_5FeSi) in Al-11.5 Si-3.8 Cu-2.6 Ni-0.5 Mg-0.45 Fe alloys were investigated and elevated temperature tensile properties of the alloy were analyzed. The microstructure was observed by optical microscope(OM) and scanning electron microscope(SEM). The phase observation and analysis of the alloy were conducted by energy dispersive spectrometer(EDS) and X-ray diffraction(XRD). The results showed that the α-Al_5FeSi phase proceeded by Ce-rich RE modification and ultrasonic field was transformed from the massive polygons to the irregular small lumps. The equal-area-circle diameter of α-Al_5FeSi phase decreased from 38.23 to 13.8 μm. The tensile strength at 350 ℃ of alloy increased from 104.1 to 116.9 MPa, and the elongation increased from 3.2% to 4.8%. The melt structure at the tip of α-Al_5FeSi phase was transformed due to enrichment of rare earth, which hampered the growth of α-Al_5FeSi phase. The spread and diffusion of solute in the solute-rich region at the solid-liquid interface was promoted because of high temperature and pressure generated by ultrasonic cavitation, which could break the α-Al_5FeSi phase to a certain degree. After the modification of rare earth, the fragmentation of the ultrasonic treatment became obvious.
引文
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[9] Yang H D, Long S Y, Zhu S Q, Fan C, Yang C Z. Effects of borides and Ce-rich mischmetal on the modification of Fe-rich intermetallics in secondary Al-Si alloys [J]. Rare Metal Materials and Engineering, 2016, (1): 187.(杨怀德, 龙思远, 朱姝晴, 范超, 杨承志. 硼化物、 富Ce混合稀土对再生Al-Si合金中富铁相变质行为的影响 [J]. 稀有金属材料与工程, 2016, (1): 187.)
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[12] Jung J G, Lee S H, Lee J M, Cho Y H, Kim S H. Improved mechanical properties of near-eutectic Al-Si piston alloy through ultrasonic melt treatment [J]. Materials Science & Engineering A, 2016, 669:187.
[13] Zhang Y B, Kateryna S, Li T J. Effect of ultrasonic treatment on formation of iron-containing intermetallic compounds in Al-Si alloys [J]. China Foundry, 2016, 42(5): 316.
[14] Li Z H, Yan H. Modification of primary α-Al, eutectic silicon and β-Al5FeSi phases in as-cast AlSi10Cu3 alloys with (La+Yb) addition [J]. Journal of Rare Earths, 2015, 33(9): 995.
[15] Sha M. The Research on Effects of Cobalt on Microstructure and Mechanical Properties of Hypereutectic Al-Si Alloy [D]. Wuhan: Huazhong University of Science and Technology, 2014. 1.(沙萌. 钴对过共晶铝硅合金微观组织和力学性能影响的研究 [D]. 武汉: 华中科技大学, 2014. 1.)
[2] Zhao M X. Research on strengthen methods and development trend of Al-Si piston alloy [J]. Automobile Applied Technology, 2015, (5): 76.(赵明欣. 活塞用铝硅合金的优化方法及发展趋势研究 [J]. 汽车实用技术, 2015, (5): 76.)
[3] Chen C J, Wang Q D, Yin D D. Research process in piston materials of combustion engine [J]. Materials Review, 2009, 23(15): 62. (陈长江, 王渠东, 尹冬弟. 内燃机活塞材料的研究进展 [J]. 材料导报, 2009, 23(15): 62.)
[4] Chen C L, Thomson R C. The combined use of EBSD and EDX analyses for the identification of complex intermetallic phases in multicomponent Al-Si piston alloys [J]. Journal of Alloys & Compounds, 2010, 490(1-2): 293.
[5] Li Y G. The Research on High Temperature Strengthening Phase of Al-Si-Cu-Ni-Mg Piston Alloy [D]. Jinan: Shandong University, 2011. 1.(李云国. Al-Si-Cu-Ni-Mg系活塞合金高温强化相的研究 [D]. 济南: 山东大学, 2011. 1.)
[6] Guo Y C, Guo S S, Li J P. Microstructure and mechanical properties of Al-Si piston alloy with different Nd contents [J]. Chinese Journal of Rare Metals, 2017, 41(10): 1069.(郭永春, 郭松松, 李建平. 稀土Nd对活塞用Al-Si合金显微组织和力学性能的影响 [J]. 稀有金属, 2017, 41(10): 1069.)
[7] Lin C. Study on the Ultrasonic Vibration Treatment and Rheological Characteristics of High Fe-Containing Hypereutectic Al-Si Alloy [D]. Wuhan: Huazhong University of Science and Technology, 2014. 1.(林冲. 高铁含量过共晶铝硅合金的超声处理及流变特性 [D]. 武汉: 华中科技大学, 2014. 1.)
[8] Liu J H. Effect of mechanical properties on Fe in rare earth hypereutectic Al-Si piston alloy [J]. Special Casting & Nonferrous Alloys,1991, (2): 14.(刘锦辉. 铁对稀土过共晶Al-Si活塞合金机械性能的影响 [J]. 特种铸造及有色合金, 1991, (2): 14.)
[9] Yang H D, Long S Y, Zhu S Q, Fan C, Yang C Z. Effects of borides and Ce-rich mischmetal on the modification of Fe-rich intermetallics in secondary Al-Si alloys [J]. Rare Metal Materials and Engineering, 2016, (1): 187.(杨怀德, 龙思远, 朱姝晴, 范超, 杨承志. 硼化物、 富Ce混合稀土对再生Al-Si合金中富铁相变质行为的影响 [J]. 稀有金属材料与工程, 2016, (1): 187.)
[10] Shi Z M, Gao K, Shi Y T. Microstructure and mechanical properties of rare-earth- modified Al-1Fe binary alloys [J]. Materials Science & Engineering A, 2015, 632(14): 62.
[11] Eskin G I. (Georgiǐ Iosifovich), Eskin D G. Ultrasonic Treatment of Light Alloy Melts [M]. CRC Press/Taylor & Francis Group, 1998. 1.
[12] Jung J G, Lee S H, Lee J M, Cho Y H, Kim S H. Improved mechanical properties of near-eutectic Al-Si piston alloy through ultrasonic melt treatment [J]. Materials Science & Engineering A, 2016, 669:187.
[13] Zhang Y B, Kateryna S, Li T J. Effect of ultrasonic treatment on formation of iron-containing intermetallic compounds in Al-Si alloys [J]. China Foundry, 2016, 42(5): 316.
[14] Li Z H, Yan H. Modification of primary α-Al, eutectic silicon and β-Al5FeSi phases in as-cast AlSi10Cu3 alloys with (La+Yb) addition [J]. Journal of Rare Earths, 2015, 33(9): 995.
[15] Sha M. The Research on Effects of Cobalt on Microstructure and Mechanical Properties of Hypereutectic Al-Si Alloy [D]. Wuhan: Huazhong University of Science and Technology, 2014. 1.(沙萌. 钴对过共晶铝硅合金微观组织和力学性能影响的研究 [D]. 武汉: 华中科技大学, 2014. 1.)
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