Evolution of Ni3X Precipitation Kinetics, Morphology and Spatial Correlations in Binary Ni-X Alloys Aged Under Externally Applied Stress

Ardell, Alan J.

University of California (System). Regents.

关键词: Nickel Base Alloys;    Binary Alloy Systems;    Aging;    Gallium Alloys;    36 Materials Science;   

DOI  :  10.2172/875895
RP-ID  :  DOE/ER/45573-1
RP-ID  :  FG02-96ER45573
RP-ID  :  875895

美国|英语

来源: UNT Digital Library

【 摘 要 】

Coarsening of Ni3Al, Ni3Ga, Ni3Ge and Ni3Si precipitates in aged binary single-crystal Ni-Al, Ni-Ga, Ni-Ge and Ni-Si alloys under applied compressive stress was measured experimentally over the temperature range 600 to 700 °C. Experiments were also performed on binary Ni-Al single crystals deformed in tension at 640 °C. The orientation of the crystals was [100] in all the experiments. Compared to the kinetics of coarsening in unstressed alloys, coarsening was slightly slower in specimens aged under compression and slightly faster in specimens aged in tension. The effect of applied stress on morphology and spatial correlation was also measured and found to be small. Ni3Al precipitates of a given size generally tended to become more non-equiaxed and their interfaces more planar, with increasing compressive stress. Ni3Ge precipitates behaved differently, becoming more spherical in specimens aged under compression. The effect of applied stress on kinetics is attributed to the influence of elastic deformation on diffusion. A model was developed that predicts slightly slower diffusion under compression and slightly faster diffusion in tension. The elastic constants of single crystals of Ni-Al, Ni-Si, Ni-Ga and Ni-Ge solid solutions were measured from room temperature to about 1100 K using resonant ultrasound spectroscopy.