Structural Changes and Sintering Characteristics of Copper-Lead Alloys by Mechanical Grinding Treatment

通过膨胀测量和组织观察，研究了机械磨削对Cu-Pb合金烧结组织和烧结特性的影响。结果表明，经高能球磨充分粉碎的合金粉末结构是由直径大于或小于50nm的微晶组成的。由此产生的铅在铜基体中的重新分布是可以接受的，因此这些粉末的烧结致密物提高了耐磨性。在氢气气氛中等时烧结MG粉末时，观察到明显的膨胀变化。在扩张曲线上观察到两个峰，第一个峰在673K，第二个峰在973K。烧结在第二峰温度以上进行，体积收缩，体积收缩量随着MG时间的延长而增加。通过观察MG粉末的等温烧结行为，对烧结机理进行了探讨。在烧结过程中，粉末压实体积的膨胀先于收缩。铜颗粒按时间的立方根增长，随后粉末压块的体积缩小。MG时间为0小时、6小时和20小时的粉末材料，颗粒生长的活化能分别为85、173和230kj/mol。认为这种活化能的差异是由于铜颗粒的形态受到MG处理的影响。

Effect of mechanical grinding (MG) on the sintered structures and sintering characteristics of the Cu-Pb alloys has been investigated by dilatometric measurements and structural observations. It was shown that the structures of the alloys powders which were sufficiently pulverized by a a ball-milling of high energy type were composed from the crystallites the diameter of which was more or less than 50nm. The resultant redistribution of Pb in the copper matrix could be so accepted that the sintered compacts of these powders improved wear resistance. A distinctive dilatometric change was observed during isochronal sintering these MG powders in hydrogen atmosphere. Two peaks were observed in the dilatation curves, the first at 673K, the second at 973K.Sintering proceeded above the second peak temperature with a shrinkage in volume, the amount of which increased with increasing MG time.Sintering mechanism has been also discussed in viewing the isothermal sintering behaviors of MG powders. During sintering the expansion preceded the shrinkage in the powder compact volume. The copper particles grew according to the cube root of time followed by a shrinkage in volume of the powder compacts. Activation energies for the particle growth were estimated to be 85, 173 and 230kj/mol for the powder compacts of MG time's 0 hr, 6 hr and 20 hr, respectively. It was suggested such a difference in the activation energy is due to the morphology of the copper partices which was affected by MG treatment.