热处理对Mg2B2O5w／AZ91D复合材料组织及性能的影响

Effects of heat treatment on microstructure and mechanical properties of Mg_2B_2O_5w/AZ91D composite

研究了固溶处理和时效处理的Mg2B2O5w/AZ91D镁基复合材料组织与显微硬度之间的关系。结果表明:经过415℃固溶处理后,共晶相的分解使复合材料的硬度明显下降。时效处理使得复合材料的硬度逐渐增加并在时效处理200℃×16h后出现时效峰值201HV,然而随着时效时间的进一步增加,显微硬度降低。经固溶处理415℃×24h,基体中-βMg17Al12相基本溶解,形成过饱和固溶体,接着时效处理8h,-βMg17Al12相以弥散形式析出,从而使得复合材料的显微硬度提高30%;而固溶处理415℃×24h,接着200℃时效处理24h后,析出相在形貌上由连续细小析出相向非连续粗大析出相过渡,这使得复合材料的显微硬度下降到183HV。

The relationship between microstructure and micro-hardness of Mg2 B2O5w/AZ91D composite heat-treated by T4, T5, T6 tempers for different time was studied. The results show that micro-hardness of the solution treated composite decreases due to resolution of eutectic phase, whereas the micro-hardness of the aged composite increases gradually and the peak hardness reachs 201 HV for the composite sample aged at 200℃ for 16 hours. Solution treatment at 415℃ for 24h,β-Mg17Al12phase is dissolved into α-Mg matrix forming supersaturated solid-solution in the composite and then the dispersed β-Mg17 Al12 phase preipitates after subsequent aging treatment at 200℃ for 8 hours, and micro-hardness of the composite increases 30% . However, as the aging time increases to 24h,hardness of the composite is reduced to 183 HV because the fine platelike β-Mg17 Al12 precipitates grow to discontinuous coarse phase.