Analysis of size distributions of primary oxide inclusions in Fe-10 mass pct Ni-M (M = Si, Ti, Al, Zr, and Ce) alloy

The planar and spatial size distributions of primary oxide inclusions were measured in an Fe-10 mass pct Ni alloy on deoxidation with 0.2 mass pct M (M = Si, Ti, Al, Zr, and Ce). It was found that the size distribution of inclusions obtained at a certain magnification in microanalysis was accurate only in a limited range of particle size, due to the limit of observation for the minimum size and observed area. The inclusion characteristics such as mean spatial diameter, (d) over bar(V), the number of particles per unit volume, N(V), and the volume fraction of particles, f(V), were estimated from the size distribution obtained in a planar cross section by using different methods. The (d) over bar(V) and N(V) values and the size distribution estimated from the cross-sectional method using different magnifications were compared with those obtained from the extraction method. The f(V) values obtained from size distribution were found to be considerably greater than those from chemical analysis of oxygen or metal element as inclusion. Furthermore, the behavior of the size distribution as a function of holding time at 1873 K is discussed.