The densification mechanism of Cu–Al mixed metal powder during a double-action die compaction was investigated by numerical simulation. The finite element method and experiment were performed to compare the effect of the forming method, such as single-action die compaction and double-action die compaction, on the properties of compact. The results showed that the latter could significantly raise the densification rate and were in good agreement with Van Der Zwan–Siskens compaction equation. The effects of the different initial packing structures on the properties of the compact were studied. The results showed that a high-performance compact could be obtained using a dense initial packing structure at a given compaction pressure. Additionally, the effects of the Al content and compaction pressure on the relative density and stress distribution were analyzed. It was observed that, with an increase in the Al content at a given compaction pressure, the relative density of the compact increased, whereas the stress decreased. Furthermore, when the Al content was fixed, the relative density and stress increased with increasing compaction pressure. The relationship between the relative density and the compaction pressure under different friction conditions was characterized and fitted according to the Van Der Zwan–Siskens compaction equation. The influence mechanisms of die wall friction on the compaction behavior were investigated. It was revealed that friction is a key factor that causes the inhomogeneity of the powder flow and stress distribution. Finally, the effects of the dwell time and height–diameter ratio on the densification behavior were analyzed, and it was found that an increase in the dwell time promoted the densification process, whereas an increase of the height–diameter ratio could hinder the process.

HA/ZrO2 composite nanpowder with various addition of titanium (0.2-2.4wt%) were synthesized via wet chemical method using ZrOCl2.8H2O, H3PO4, Ca(OH)2 and tetraethylorthotitanate as precursor materials. The composites were then sintered at 900-1200?C for 2h, respectively. Effect of titanium addition to the composite on the phase composition and thermal stability during thermal treatment was investigated. The results suggested that as the sintering temperature increased from 900?C to 1200?C and with the addition of titanium to the composite below 0.8wt%, main phases were HA and ZrO2. As the sintering temperature increased to 1200?C and with the addition of titanium to the composite above 0.8wt%, main phases were HA, ZrO2 and a small amount of dicalcium phosphate (DCP). There were still no tricalcium phosphate (?-TCP) and CaZrO3 phases observed, which indicated that the addition of titanium restrained decomposition of HA and thermal reaction between HA and ZrO2. It also suggested that the addition of 0.8wt% titanium to the composite was optimum for producing HA/ZrO2 composite nanopowder with expected main phases. With the addition of 0.8wt% titanium to the composite, SEM images showed that the individual particles of the two materials were still visible, which also implied that the reaction between HA and ZrO2 did not occur.

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