大尺寸耐热铝合金管坯的致密化及性能研究

Densification Process and Mechanical Properties of Large Dimension Heat-resistant Al Alloy Pipe Blank

通过金相显微镜、扫描电镜、透射电镜等对多层喷射沉积制备的大尺寸耐热铝合金管坯及其经过挤压、旋压等致密化加工后的显微组织结构进行了检测和分析,并通过Instron拉伸实验对致密化加工过程中管坯的力学性能进行了比较.喷射沉积管坯的致密度约为88.9%,晶粒为200nm～500nm的微晶,20nm～60nm的球形或近球形析出相均匀分布于基体上.经过热致密化加工后管坯中的界面和孔洞明显愈合,析出相未见明显粗化.管坯经过挤压后,室温和350℃的断裂强度分别提高130%和400%.挤压管材旋压后,350℃力学性能变化不大,而室温屈服强度和断裂强度分别提高22%和13%.

The microstructure of the multilayer spray deposited, extruded and spanned pipe blanks of the heatresistant Al alloy was examined and analyzed by light optical microscope, transmission electronics microscope and scanning electronics microscope. The effects of densification technologies on the mechanical properties of the pipe blanks were also tested by Instron tensile machine. The densification degree of the deposited pipe blank is about 88.9%,the diameters of the fine grains are about 200 nm^500 nm with particulates about 20 nm^60 nm uniformly distributed. The interface and micro holes were welded and no distinct coarseness was occurred after heat densification processing. After extrusion, the alloy's fracture strengths at room temperature and 350℃ are improved about 130% and 400%, respectively. Followed by further span, the alloy's strength shows little increase at 350℃, while the yield strengths and the fracture strength increase about 22 and 13% at room temperature, respectively. 