Precision Measurements of Gamma Prime Coarsening at Low Volume Fractions in Nickel-Base Alloys

该程序研究了二元金属合金中析出相粗化的机理。现有理论预测，析出相的粗化行为受析出相体积分数的影响。这种效果应该在低体积分数时最大化。在本研究中，采用预时效处理使金属基体成分均匀。该处理之后进行高温时效处理，以控制析出相生长动力学和粒度分布。采用透射电子显微镜和磁性技术检测金属合金试样，测定析出物体积分数和生长速率。相关的理论考虑考虑了相干应变对粗化过程的影响。正在研究的金属合金是镍与铝、硅或钛的二元化合物。

The program investigates the mechanisms of coarsening of precipitates in binary metal alloys. Existing theories predict that precipitate coarsening behavior is influenced by the volume fraction of precipitate. This effect should be maximized at low volume fractions. In this research pre-aging treatments are employed to produce a uniform composition in the metal matrix. This treatment is followed by an elevated temperature aging treatment to control the kinetics of precipitate growth and the particle size distributions. Metal alloy specimens are examined by transmission electron microscopy and magnetic techniques to measure precipitate volume fraction and growth rate. Related theoretical considerations take into account effects of coherency strains on the coarsening process. The metal alloys under investigation are binaries of nickel with additions of aluminum, silicon or titanium.