摘要
利用电子束物理气相沉积(EB-PVD)方法制备出厚度为0.5mm的Ni-Cr-Al高温合金。研究了该合金在制备状态和长期时效后的显微组织及其力学性能。结果表明,制备态合金表面的晶粒尺寸约为185nm,并且材料断面呈层状结构。合金在760℃下时效16h,72h和120h后,材料断面的层状结构消失,且明显看到晶粒的存在。合金时效16h后,在靠近基板一侧形成柱状晶,但远离基板一侧为等轴晶。760℃长时间时效形成的主要强化相为γ'相。断口结果表明,制备态合金室温断口为混合型断口,接近基板一侧发生沿柱状晶边界的脆性断裂,而在另一侧为韧窝为主的韧性断裂。材料经长时间的真空时效后,断口由脆性断口转变为韧性断口。合金的室温显微硬度随时效时间的增加而下降,这是由于γ'相不断长大所引起。与制备态合金相比,时效后合金的力学性能明显改善。
Ni-Cr-Al alloy with 0.5 mm thickness was deposited by EB-PVD process. Microstructure and mechanical properties were investigated on as-deposited and long-term aged alloy. The results indicate that grain size on surface of as-deposited alloy was about 185 nm, and a laminated structure in cross-section was observed. After aging for 16 h, 72 h, 120 h at 760°C, the laminated structure was dissolved, and the individual grains can been seen clearly. Columnar crystals formed in the surface of alloy adjacent to the substrate, and equiaxed grains apart from the substrate for the alloy after aging for 16 h. The major precipitate was γ′ phase after prolonged aging at 760°C. Fractographs of as-deposited alloy show that the fracture was mixed type at room temperature. Brittle fracture took place along boundaries of columnar crystals formed in the side adjacent to the substrate. However, in the side apart from the substrate the equiaxed dimples were dominant. Brittle-ductile transition occurred after aging treatment in vacuum condition. Room temperature microhardness of alloy decreased with an increase in temperature mainly due to the growth of γ′ phases. Test results show that compared with as-deposited alloy, mechanical properties of annealed alloy were improved significantly.
出处
《航空材料学报》
EI
CAS
CSCD
2005年第1期11-14,共4页
Journal of Aeronautical Materials
基金
国家自然科学基金项目(50304007)
关键词
电子束物理气相沉积
显微组织
力学性能
柱状晶
镍-铬-铝
高温合金
航空材料
Aging of materials
Crystallization
Fracture
Grain size and shape
Mechanical properties
Microhardness
Microstructure
Nickel alloys
Physical vapor deposition
