Microsegration and homogenization of Ni-7.5wt%Al-2.0wt%Ta dendritic monocrystals

Study by Differential Thermal Analysis of Reverse Spinodal Transformation in 15-5 PH Alloy.

“…because of the nonisothermal process [11]. With L of the order of 10 nm and using the diffusion coefficient of Fe measured by Ray and Sharma [12] for a Fe-Cr alloy with 10 wt.% Cr, the integration between 400°C and 550°C at a heating rate of 5 K/min gives a value of α of about 5.…”

Energy Saving Melting and Revert Reduction (E-SMARRT): Optimization of Heat Treatments on Stainless Steel Castings for Improved Corrosion Resistance and Mechanical Properties

“…For typical alloys, where k (the equilibrium partition coefficient ) < 1 , the segregation profile is such that the concentration of critical alloying elements is minimum at the dendrite cores and maximum in the interdendritic regions [23,24].…”

“…A homogenization treatment entails exposing a casting to an elevated temperature for a prolonged period to allow segregated alloying elements to diffuse down the chemical gradient and eliminate the concentration profile [23][24][25]. The relative effectiveness of the homogenization heat treatment can be characterized by the index of residual segregation, which is a ratio of the amount of segregation after a homogenization treatment to the initial amount of segregation:…”

“…where C M θ and C m θ represent the maximum and minimum concentration after a given homogenization time and C M 0 and C m 0 represent the maximum and minimum initial concentration [23][24][25]. Thus, in the assolidified condition δ =1 and will decrease to zero for a fully homogenized alloy with no composition gradient.…”