Direct Energy Deposition has been employed to produce M300 samples in two optical configurations. Process parameters effects on the quality of the printed parts have been studied, analysing the relashionship with the microstructure. The same samples have been produced in both free atmosphere and inert chamber . Primary cellular arm spacing has been computed also for the evaluation of the cooling rate at different height of the specimens. It has been found that the two atmosphere show opposite trends. In free atmosphere the PCAS increases from 8um to 13.5um. Using the airtight room insted it decreases from 6um to 4um for the different cooling rates.