Processing and characterization of cluster diamond dispersed Al–Si–Cu–Mg composite

Cluster diamond (CD), which consists of ultra-fine diamond particles with a mean particle size of 5 nm, shows excellent lubricating ability. By dispersing CD in metals, metal matrix composites that have low friction and good wear properties can be produced with self-lubricating ability. In the present study, CD-dispersed Al–Si–Cu–Mg alloy-based matrix composites were fabricated by the powder metallurgy method. The mixing of CD and Al–Si–Cu–Mg alloy powders was carried out by the mechanical milling method. The amount of CD added was varied from 0 to 10% by volume. The mixed composite powders were consolidated at 773 K by hot pressing in a vacuum. X-ray diffraction analysis showed that the added CD had not changed in structure after the consolidation process. Friction measurements were performed at 1.7 mm/s and 0.2 N by the pin-on-disc method to measure the friction coefficient and wear width of consolidated Al–Si–Cu–Mg/CD composite powders. The results showed that the addition of 1 vol.% CD to Al–Si–Cu–Mg alloy significantly improved the friction coefficient compared to that of Al–Si–Cu–Mg alloy. Furthermore, the addition of graphite CD (GCD) achieved a friction coefficient of 0.14. However, the friction coefficient and wear width deteriorated with an increase in the volume fraction of CD or GCD.