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

通过膨胀测量和组织观察，研究了机械研磨对铜铅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由直径大于或小于50 nm的微晶组成。由此产生的铅在铜基中的重新分布是可以接受的，这些粉末的烧结体提高了耐磨性。在氢气气氛中等时烧结过程中观察到了明显的膨胀变化。在膨胀曲线上观察到两个峰值，第一个峰值在673K，第二个峰值在973K。在第二个峰值温度以上烧结，体积收缩，收缩的数量随着MG时间的增加而增加。在烧结过程中，膨胀先于粉末压实体积的收缩。铜颗粒按照时间的立方根生长，随后粉末压坯的体积收缩。对于MG时间为0小时、6小时和20小时的粉末压坯，颗粒生长的激活能分别为85、173和230kJ/mol。结果表明，活化能的差异是由于MG处理影响了铜颗粒的形态。

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.