钛基复合材料棒材包套热挤压制备及组织性能研究

发布时间：2018-06-14 16:37

  本文选题：钛基复合材料 + 包套热挤压　； 参考：《哈尔滨工业大学》2015年硕士论文

【摘要】：Ti B陶瓷增强钛基复合材料因其优异的耐磨性、耐腐蚀性及高的比强度等优点,在航空航天及军工领域有着广阔的应用前景。目前主要通过真空热压烧结、热等静压等工艺实现,但因其工艺复杂、设备昂贵、效率低下,极大地限制了其规模化应用。本文基于前期研究,提出了“高温短时预烧结+包套热挤压”工艺,实现了对Ti Bw/Ti-6Al-4V复合材料棒材制备工艺的进一步优化,成功获得组织致密、塑性良好复合材料棒材,并深入研究了挤压温度对其组织性能影响,同时探索了B元素对于Ti-6Al-4V基体组织的影响。采用“高温短时预烧结+包套热挤压”工艺,成功制备出了Φ12×220mm的Ti Bw/Ti-6Al-4V复合材料棒材。1200℃短时预烧结可加速原位反应进行、明显提升材料致密度,使钛基复合材料棒材的生产效率大幅提升。工艺改进后材料的室温塑性提升明显,当挤压温度为950℃和1150℃时,复合材料的伸长率分别为5.08%和7.83%,达到了伸长率5%的预期目标。深入研究挤压温度950℃~1150℃对Ti Bw/Ti-6Al-4V复合材料棒材组织性能影响。随温度升高,复合材料内Ti B晶须数量逐渐下降,长径比明显提升;基体伸长型α相逐渐转变为α集束和晶界α相,并且基体中β相的数量也有所增加。当挤压温度为950℃时,基体中表现出了较强烈的1010织构,此时材料的室温抗拉强度达到1171.8MPa。当挤压温度为1050℃时,基体α相表现出了强烈的0001和1010织构,此时的抗拉强度为1191.2MPa。当挤压温度为1150℃时,基体中α相表现出了0001和1011织构,这时材料的抗拉强度达到1156.3MPa。三种材料的延伸率分别为5.08%、2.32%、7.83%。对比分析Ti-6Al-4V合金发现:B元素使得基体中α相明显细化,并且在Ti B晶须附近基体的α片层球化现象更加明显。当挤压温度为950℃时,材料塑性变形处于(α+β)双相区,B元素的存在显著提升了Ti Bw/Ti-6Al-4V复合材料基体的β转变温度,使得基体中初生α相的1010织构强度更高。并且大幅提升了Ti-6Al-4V基体的室温拉伸性能。
[Abstract]:Due to its excellent wear resistance, corrosion resistance and high specific strength, TiB ceramic reinforced titanium matrix composites have a wide application prospect in aerospace and military industry. At present, it is mainly realized by vacuum hot pressing sintering and hot isostatic pressing, but because of its complex process, expensive equipment and low efficiency, its application on a large scale is greatly limited. In this paper, based on the previous research, the "hot extrusion process of high temperature and short time pre-sintering ladle shell" is proposed, which realizes the further optimization of the preparation process of Ti BW / Ti-6Al-4V composite rod, and obtains the compact microstructure and good plasticity of the composite rod successfully. The effect of extrusion temperature on the microstructure and properties of Ti-6Al-4V matrix was studied, and the effect of B element on the microstructure of Ti-6Al-4V matrix was investigated. By means of "hot extrusion of high temperature short-time pre-sintered ladle", Ti BW / Ti-6Al-4V composite bar with 桅 12 脳 220mm has been prepared successfully. Short-time pre-sintering at 1200 鈩，

本文编号：2018182