PMC

Mass distribution of metals Al, Fe, and Zn from the WRASS stages (Dp, aerodynamic diameter).

Schematic of FSW apparatus: (a) tool and workpiece geometry and (b) sampling geometry.

Particle size distribution obtained from the ESP (Case 1, source) presented in .

Field emission scanning electron microscopy SEIs of representative fields collected during Case 1: (a) collected with the ESP at the source; (b) collected with the TP at the BZ.

Typical size distribution (dN/dLog Dp, particle number per cubic millimeter) near the source for Case 1 as a function of time; (a) EEPS (Dp = electrical mobility diameter); (b) APS (Dp = aerodynamic diameter).

Particles collected with the ESP at the source and with the TP at the BZ for Case 1: (a and b) 60 nm diameter spherical Fe particle, from source, attached to a SiO² flake; (c and d) Ni particle, from source; (e and f) Zn particle, from BZ; (g and h) large Al particle, from BZ.

Aluminum particles collected with ESP (Case 1, source): (a) Typical Al particle field emission scanning electron microscopy (FESEM) image; (b) EDS from (a) showing presence of major elements (Mg and Al) present in 6061-T6 aluminum. (c) FESEM image of a larger particle; (d) EDS from (c) showing high Al content.

Average size distribution (dN/dLog Dp) at (a) source and (b) BZ. The y-axis represents the relative particle number concentration, whereas the x-axis the channel midpoint. Each data point is the arithmetic mean of that channel value over five replicate tests. Standard errors of the mean have been omitted for clarity purposes. The EEPS measures the electrical mobility diameter, whereas the APS the aerodynamic diameter. Little overlap between two size distribution ranges and the different principles for measuring Dp may explain the dip at ∼600 nm. Case 1A through 2B are defined in .