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A D V A N C E D M A T E R I A L S & P R O C E S S E S | J U L Y / A U G U S T 2 0 1 8 4 6 iTSSe TSS iTSSe TSS to the bonding and fatigue properties, depending on the substrate’s material properties. Mahmoudi-Asl studied the resid- ual stress in a cold spray magnesium AZ31 alloy, compared the stress in the as-sprayed and stress-relieved condi- tions, and compared the experimental values with those of the stress state obtained by means of finite element modeling. The overall study was to predict and measure the effect of the cold spray coating on the fatigue be- havior of a self-mated magnesium alloy. Luzin et al. used neutron diffrac- tion to determine the residual stress of thick coatings ( ∼ 0.5 mm, or 0.02 in.). Neutron diffraction is nonde- structive and is considered the most direct way to measure stress, espe- cially because it is phase sensitive and the stresses can be assessed for each phase independently. Addition- ally, no specific sample preparation is required for neutron diffraction. The study evaluates copper and alumi- num coatings on aluminum (alumi- num-magnesium alloy) and copper substrates. There have also been re- ports of using the in situ coating prop- erty sensor to evaluate the deposition stress of the coating as the coating is deposited. Thus, regardless of the method used, it is important to char- acterize the coating’s residual stress in the as-sprayed condi- tion as well as at the application temperature to assess overall coating reliability. ~iTSSe For more information: This article series is adapted from Chapter 5, Cold Spray—Advanced Characterization authored Fig. 3 — Through-thickness residual stress in a cold spray IN625 and Ni-20Cr coating (a) in the as- sprayed versus heat treated (HT) condition and (b) using helium versus nitrogen as process gas, in each case measured using the x-ray diffraction sin 2 Ψ method. (a) (b) by Dheepa Srinivasan, in High Pressure Cold Spray—Principles and Applications, edited by Charles M. Kay and J. Karthikey- an (ASM, 2016). Complete references are included in this vol- ume. The author may be reached at dheepasrinivasan6@ gmail.com . FEATURE 12