EXPERIMENTAL-STUDY OF PRECIPITATION IN AN ION-IMPLANTED METAL - SB IN AL

The formation and evolution of AlSb precipitates in Sb-implanted Al has been investigated as a function of temperature, flux, and fluence. Implant temperatures of 23-300°C, fluxes of 6×1011 to 1.3×1013 Sb cm-2 sec-1, and fluences of 5×1015 to 2×1017 Sb cm-2 were investigated, and transmission electron microscopy was used to detect the precipitates and to determine their size distributions. The AlSb precipitate mean size becomes larger and the number density decreases with increasing Sb implantation temperature, with increasing fluence, and with decreasing flux. The temperature and flux dependences of the evolution are large for 5×10 15 Sb cm-2 added to initially pure Al, and are much weaker at higher fluences where 1.5×1015 Sb cm-2 has been added to a preexisting precipitate distribution. This indicates that flux and temperature affect the size distribution most strongly during nucleation and/or early growth. Ion damage has been demonstrated to be a significant factor in the precipitate evolution through Ar and Al bombardment of preexisting precipitates. At 300°C self-ion bombardment leads to ripening, whereas the precipitate size distribution is stable in the absence of implantation. At room temperature, Ar irradiation causes the AlSb diffraction pattern to disappear at ∼1 displacement per atom (dpa) independent of precipitate size, suggesting that here destruction of precipitates occurs due to disordering of the AlSb lattice. The results are discussed in terms of thermal and irradiation-induced processes.