A: Yes, if you heat them beyond 170 degrees Fahrenheit (80 degrees Celsius) the magnets will quickly loose their magnetic properties. Sustaining these temperatures for a length of time or heating the magnet significantly higher than this will permanently demagnetize it. Other types of magnets such as Samarium-Cobalt have higher heat resistance(below 300 degree Celsius). There are also other types of Nd-Fe-B magnets that are not as susceptible to heat induced flux degradation,H grade could withstand 100 degree Celsius,SH grade 150 ^oC ,UH grade 180^oC,and EH grade 200^oC.