摘要
采用熔体旋甩法制备了快速凝固Al87Ni7Cu3Nd3金属玻璃薄带,并以连续加热和等温加热两种模式对非晶态薄带进行退火处理。采用差示扫描量热分析、X 射线衍射分析和高分辨率电镜分析等手段研究了非晶态薄带的晶化过程,对非晶态和退火态薄带的微观结构进行了细致检测,研究重点放在形成α Al纳米晶体颗粒的初始晶化行为,以便了解Al基纳米晶/非晶复合材料的结构特征。结果表明,快速凝固Al87Ni7Cu3Nd3合金薄带为单一的非晶态结构。非晶态薄带的晶化过程包括两个主要转变:α Al晶体从非晶基体中析出的初始晶化以及有Al3Ni,Al11Nd3和Al8Cu3Nd形成的第二次晶化过程。初始晶化的速率控制过程可能是铝自扩散,而第二次晶化过程则受控于溶质原子Ni,Nd和Cu的扩散。90～160℃等温退火薄带由α Al晶体相加残余非晶相的两相组织构成,随着等温温度的提高,初始晶化过程速率增大,而随着退火时间的延长,α Al晶体相的相对含量增大。110℃等温热暴露130min退火薄带的显微组织可以描述为,在非晶基体上均匀弥散分布着体积分数约20%的α Al晶体纳米(10nm)颗粒。
Rapidly solidified Al_(87)Ni_7Cu_3Nd_3 metallic glass ribbons were prepared by using melt spinning, and were annealed under both continuous heating and isothermal heating regime. The amorphous ribbons and the annealed samples were examined by means of differential scanning calorimetry, conventional X-ray diffraction, and high resolution transmission electron microscopy with selected-(area) electron diffraction, with special interest in primary crystallization into α-Al nanocrystalline particles, in order to understand structural characteristics of the aluminium based amorphous composites with nanocrystal particles. The results show that, the as-spun ribbons are fully amorphous in the micron scale. The metallic glass ribbons devitrify via two main stages: primary crystallization, resulting in α-Al crystal particles precipitation from the amorphous matrix, and secondary crystallization, corresponding to some inter-metallic phases appearing, including Al_3Ni, Al_(11)Nd_3, and Al_8Cu_2Nd. The rate-controlling process of the primary crystallization is self-diffusion of Al atoms and the secondary crystallization is limited by bulk diffusion of the Ni,Nd and Cu solute atoms. The ribbons annealed isothermally at the temperature of 90～160℃ consist of two-phase mixture of the α-Al crystal phase and the residual amorphous phase. The primary crystallization will occur at an increasing rate with isothermal temperature improving, and the α-Al crystal relative amount will increase with annealing time prolonging. The typical microstructures of the annealed ribbons exposed isothermally at 110℃ for 130 minutes can be characterized as, high volume fraction (20%) of α-Al crystal nanometer (10nm) particles disperse uniformly in an amorphous matrix.
出处
《航空材料学报》
EI
CAS
CSCD
2004年第4期39-44,共6页
Journal of Aeronautical Materials
基金
国家重点基础研究发展规划资助项目(G199906 4900)
