通过场发射扫描电子显微镜(FESEM),X射线衍射仪(XRD),能量色谱仪(EDS)分析Al-5Ti-1B,Al-4Ti-1C和Al-5Ti-0.8B-0.2C中间合金的微观组织与物相组成,比较研究3种中间合金对7050铝合金晶粒尺寸与力学性能的影响.结果表明:Zr的存在削弱了Al-5Ti-1B和Al-4Ti-1C中间合金的细化效果,而对Al-5Ti-0.8B-0.2C中间合金细化效果影响较小.含掺杂型TiC粒子的Al-5Ti-0.8B-0.2C中间合金具有较好的抗Zr"中毒"能力,加入量为0.2%(质量分数,下同)时,含Zr7050铝合金平均晶粒尺寸由200μm细化至(60±5)μm,室温极限抗拉强度由405MPa提高到515MPa,提高了27.2%,伸长率由2.1%提高到4.1%.而加入0.2%的Al-5Ti-1B或Al-4Ti-1C中间合金时晶粒尺寸较粗大且分布不均匀,表现出明显的细化"中毒".
The microstructure and phase composition of Al-5Ti-1B, Al-4Ti-1C and Al-5Ti-0.8B-0.2C master alloys were investigated by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS), and the effects of the three kinds of master alloys on the grain size and mechanical properties of 7050 alloy were investigated.The results show that the existence of Zr reduces the grain refining effects of Al-5Ti-1B and Al-4Ti-1C master alloys, but hardly influences the refinement of Al-5Ti-0.8B-0.2C master alloy.The reason is that Al-5Ti-0.8B-0.2C containing B-doped TiC can resist Zr-poisoning, and after adding 0.2% (mass fraction) Al-5Ti-0.8B-0.2C, the average grain size of 7050 alloy is reduced from about 200μm to (60±5)μm, the ultimate tensile strength increases from 405MPa to 515MPa, increasing by 27.2%, and the elongation rate increases from 2.1% to 4.1%.However, after adding 0.2% Al-5Ti-1B and Al-4Ti-1C master alloys, the grain size is larger and the distribution is uneven, exhibiting obvious "refinement poisoning" phenomenon.
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