Effect of nano-alumina concentration on annealing behaviors of dispersion strengthened copper alloys

Annealing behaviors of low and middle alumina cocentration dispersion strengthened copper alloys(DSCAs) were studied by mechanical properties measurment and OM,TEM observation.The results show:the resistance to softening at high temperature is not very strong for low alumina concentration DSCA,recrystation occurs as annealing at 500℃,and complete recrystation at 900℃,yield ratio reachs 56%.The resistance to softening at high temperature is much stronger for middle alumina concentration DSCA,only recovery occurs as annealing at 900℃,recrystal grains can not be observed through OM,and yield ratio is about 70%.The stronger resistance to softening at high temperature for DSCA is due to nano-alumina particles distributing in the copper matrix.As alumina particle size being 10～20nm,the resistance of particles to retard crystal boundary migration is poor when interval space is longer than 200nm and when internal space of particles is shorter than 90nm,the resitance is strong.