【作者】 张建会；

【导师】 雷玉成；

【作者基本信息】 江苏大学 ， 材料加工工程， 2007， 硕士

【摘要】 SiCp／Al基复合材料由于具有高的比强度、比刚度、比模量，尺寸稳定性以及抗振、耐高温，不老化，抗宇宙射线等优点，在航天、航空、汽车、电子等工业领域具有广泛的应用价值，成为当前金属基复合材料发展与研究工作的主流。但是由于铝基复合材料基体和增强相之间热物理、化学性能的巨大差异，在高温下极易发生界面反应生成脆性相Al₄C₃，不仅很难形成优质的焊接接头，而且使焊缝力学性能严重降低，严重制约了SiCp／Al基复合材料的应用，因此应尽量避免这种脆性相的生成。本文以SiCp／6061A1MMCs为研究对象，采用等离子弧焊接工艺研究了SiCp／Al复合材料的可焊性。分别以Ti和混合粉末为填充材料，以N₂+Ar的混合气为离子气对复合材料进行焊接。通过拉伸试验、显微硬度测试、金相观察、扫描电镜（SEM）、X射线衍射（XRD）分析，系统研究了不同合金元素对焊缝组织和性能的影响。研究结果表明，在填加Ti做填充材料的情况下，能有效抑制界面反应，并生成了新的增强相颗粒，焊缝显微组织良好，焊接接头强度达到母材的50.89％，显微硬度在焊缝中心区域达到最大值。分别以Ti-Si、Ti-Mg、Ti-Cu的混合粉末为填充材料对SiCp／6061A1MMCs进行等离子弧焊接时，填加的合金元素都能提高Al对SiC颗粒的润湿性，获得结合紧密的界面。其中Ti-Si和Ti-Mg的效果较好，拉伸强度分别达到232.2Mpa和204.7Mpa，拉伸断口呈现出一定的韧性断裂特征；而加入Ti-Cu时，由于没有完全抑制针状有害相Al₄C₃的形成以及Al₂Cu的生成，拉伸强度仅为187.5MPa，断口为明显的脆性断口。当采用不同的焊接电流、焊接速度和离子气配比进行焊接时，接头抗拉强度变化明显，试验得出获得较高性能焊接接头的工艺参数为：I=120A，V=140mm／min，N₂体积含量为15％。加入合金元素后，提高了焊缝金属凝固结晶速度，改善了基体金属对增强颗粒的润湿性，增加增强相颗粒在焊缝金属中分布的均匀性，并减少了颗粒偏聚的倾向，有利于获得了高质量的焊接接头。更多还原

【Abstract】 SiCp/Al metal matrix composites （SiCp/Al MMC_S） are wildly applied in aerospace, automobile and electron industry owing to their excellent properties, including high specific strength, specific stiffness and specific modulus, attractive dimension stability and vibration resistance, high temperature resistance, corrosion resistance and radiation resistance, etc. However, on account of much difference in the heat physical and chemical performance of reinforcement and matrix, and due to the possible formation of brittle reaction product, Al₄C₃, by interfacial reaction in high temperature, it is hardly to form high-quality welding joint, and reduces the mechanical property of weld greatly, which is confining the development of SiC_P/Al composites. So the key problem is avoiding or decreasing the formation of brittle product.In this paper, the weldability of SiC_P/Al composites was studied by the technology of plasma arc welding through SiCp/6061AlMMCs. The composites was welded in the way that titanium and mixed powders were used as alloying filler metal and N₂ and Ar were used as the plasma gas. The influence of different alloy metals on weld organization and performance were systematically investigated by tensile and microhardness tests, OM, SEM, EDS and XRD analysis.The results showed that interface reaction was effectively controlled with titanium as the filler metal and the new reinforcing phases were generated, the microstructure of welding line was dense and the tensile strength obtained 50.89% of basic metal, the microhardness reached maximum in the middle of welding line.The filler metals all could reform wetting property of Al to SiC in order to form well-knit interface while Ti-Si、Ti-Mg and Ti-Cu mixed powders were employed as filler metals to PAW SiCp/Al MMC_S. The effect indicated that the preferable tensile strength achieved 232.2Mpa and 204.7Mpa respectively when Ti-Si and Ti-Mg mixed powders put into weld crater, and the fracture present gliding fracture character; however, the tensile strength only achieved 187.5MPa because of the formation of needle-like harmful phase Al₄C₃ and Al₂Cu, and the fracture was visible rock-candy structure. The tensile strength changed distinctly when different welding current, welding velocity and plasma gas match were adopted in welding. The technologic parameters to achieve high performance joint were that welding current was 120A, welding velocity was 140mm/min and the nitrogen volume content was 15%.The high quality welding joint was attained easily on account of alloy filler metals, which improved the solidification and crystallization velocity of molten pool, reformed improve wetting property of basic metal to reinforcing phase, made reinforcing phase particles distributing equably in welding line and reduce the tendency of granules.更多还原