Analysis procedure and bronze oxidation temperature

I am a technician in an R&D lab. I work for a hydraulic seals manufacturer. Some of the compounds we make use bronze fillers. I would like to determine the percentage of bronze (as well as other fillers--glass, carbon, mineral . . .) using Thermal Gravimetric Analysis (TGA). Since bronze oxidizes in the presence of oxygen (which shows an increase on TGA curve) it is difficult to determine the percentage of bronze and other fillers in a compound. I am trying to react all the bronze in my sample then continue with the heating ramp in air (I typically heat to 650°C in nitrogen then switch to air). So here is what I would like to know before I spend more time on this project.

What temperature does bronze begin oxidation? Is the oxidation a continuous process as temperature increases? OR Is there a specific temperature at which all of the bronze in a sample will oxidize, then no more oxidation will occur as temperature increases?

Thank you for your time and insight,