Aluminum Nitride in Al–Si–Mg Alloy

Abstract When liquid aluminum is exposed to air, an oxide layer instantaneously forms on the surface of melt, which, when enfolded, becomes a double film defect (bifilm), producing entrained air pockets forming voids, cracks, and areas stress. Studies reactions between trapped inside bifilms surrounding melt have produced reaction products such as AlN. In this study, examination fracture surfaces Al–7Si–0.3Mg (2L99) as-cast alloy revealed AlN apparently different “nodular” morphology approximately 15 μ m in length. contrast “feather-shaped” grown through holding nitrogen or addition Mo 2L99 observed previous research, nodular study was thought be less permeable. This confirmed hypothesis Nyahumwa et al . (AFS Trans 106:215–223, 1998), who suggested that entrapped can react with by initially consuming oxygen form oxides, spinel (MgAl 2 O 4 ), followed consumption The has been proposed reduce size correspondingly improve mechanical properties alloy. work, also alloys controlled gas environment at 850 °C various times reveal morphologies.