We developed an x-ray diffraction (XRD) method that uses relative satellite peak intensities to assess the width of the alloy interfaces in InAs/InAsSb Type 2 superlattices (T2SLs). Specifically, our method simulates XRD patterns for T2SLs based on a model of alloy cross-incorporation and fits the simulated pattern to experimental data through a small set of model parameters. We model the Sb distribution function with two forms (i) a Gaussian function, or (ii) two error functions. We compared the model with experimental data extracted from the literature. The first example is a T2SL with 50 periods of 7.0 nm thick InAs and 2.3 nm thick InAs1-xSbx with the targeted alloy composition of x = 0.23. The second example is a T2SL with 100 periods of 4.6 nm thick InAs and 1.7 nm thick InAs1-xSbx with the targeted composition of x = 33.3%. The width of the alloy interface is about 2.54 nm for the first example with the Gaussian model, and with the error function model is 2.8 nm. In the second example, we observed a lower width of the alloy interface of about 0.48 nm with the Gaussian model, and 0.5 nm with the error function model.