(100) Fe films deposited on (100) Pd, Ag, Au and Pt seed layers, with the latter metals deposited on (100) Si with proper respective seed layers, have been heated to 600°C, and their thermal stabilities assessed. The Fe layers were found to stay little changed, both structurally and magnetically, up to an anneal of 30 min around 400°C. At higher temperatures, the Fe layers change in structure and degrade magnetically, but with different mechanisms for different structures. For the ones with Pt or only with Pd, the consumption of the metal layers for the suicide formation below 400°C causes less changes of the Fe layers than those in the other structures. For the one with Ag, Fe apparently mixes with Ag above 400°C, with Ag being nearly intact up to 600°C, resulting in a rapidly decreasing magnetic moment of Fe. For the structure with Au, the formation of the Au-Si eutectic melt at 363°C completely destroys the structure and magnetic moment of Fe above 400°C.