旋压加工对喷射沉积Al-8.5Fe-1.3V-1.7Si合金挤压管组织和性能的影响

Effects of shear spinning process on microstructures and mechanical properties of extruded pipes of spray deposited Al-8.5Fe-1.3V-1.7Si alloy

采用喷射沉积-热挤压工艺制备快速凝固Al8.5Fe1.3V1.7Si耐热合金管材,并通过强力热反旋压工艺将这些挤压管进行多道次减薄,制备薄壁管;利用金相显微组织观察、透射电镜分析、扫描电镜分析和力学拉伸试验等手段,研究强力热反旋压工艺对喷射沉积Al8.5Fe1.3V1.7Si合金挤压管材显微组织和力学性能的影响。研究结果表明喷射沉积Al8.5Fe1.3V1.7Si挤压管的显微组织呈纤维条带状,不同条带中Al12(Fe,V)3Si(体心立方,a≈1.260nm)颗粒大小和分布形貌不同,甚至出现θAl13Fe4(底心单斜,a=1.543nm,b=0.812nm,c=1.254nm,β=107.43°)和Al8Fe2Si(六方,a=1.270nm,c=2.620nm)粗块状相;条带间残留着未充分破碎的氧化物和原始粉末界面;在强力旋压过程中,条带状组织发生畸变,氧化膜破碎,并重新分布,弱结合的残留原始粉末界面减少或消失,显微组织趋于连续、均匀;与其他挤压管材相比,喷射沉积Al8.5Fe1.3V1.7Si合金旋压管材,力学性能明显提高,材料各向异性有所减弱。

Extruded pipes of rapidly solidified Al-8.5Fe-1.3V-1.7Si alloy were prepared by using spray deposition and hot extrusion process, and the extrusions were thinned further into thin-wall pipes through hot backward shear spinning process. The effect of shear spinning process on microstructures and mechanical properties of extruded pipes of spray deposited Al-8.5Fe-1.3V-1.7Si alloy were investigated with optical microscopy, transmission electron microscopy, scanning electron microscopy and tensile test. The results show that the extruded pipes of spray deposited Al-8.5Fe-1.3V-1.7Si alloy consist of fibre (strip) microstructures, and distribution, size and shape of Al12(Fe, V)3Si (body center cubic structure, a=1.260 nm) particles are various in the different fibre strips, and there even appear θ-Al3Fe4 (bottom-central monoclinic structure, a=1.543 nm, b=0.812 nm, c=1.254 nm, β=107.43°) and Al8Fe2Si (hexagonal structure, a=1.270 nm, c=2.620 nm) coarse lumpish phases. The insufficiently broken pieces of oxide films and incompletely binding prior particle boundaries remain along interface among the fibre strips. During the shear spinning process, the fibre (strip) microstructures are severely distorted, the oxide broken pieces are further cracked and redistributed, the weak binding prior particle boundaries are reduced and disappeared, and the overall microstructures incline to become a more uniformly continuum. All of these microstructural changes help to improve mechanical properties of the extruded pipes of spray deposited Al-8.5Fe-1.3V-1.7Si alloy and weaken anisotropy of the materials.