A microsegregation model with local partition coefficients and temperature-dependent diffusion coefficients based on the model of Ohnaka (I. Ohnaka, Trans. Iron Steel Ins. Jpn. 1986, 26, 1045) is proposed. In this model, multicomponent alloy effects and precipitations are considered, and the peritectic reaction can be indicated using the thermodynamic library ChemApp. The proposed model is validated by comparing the results to other models from the literature and to measured data. Local partition coefficients are calculated, and their significant influence on microsegregation prediction is shown. The characteristic temperatures determined using the proposed model are in good agreement with measured values.