Powder metallurgy processing of Mo-Cu for thermal management applications

Mo-Cu is desirable for thermal management applications because of its combi nation of low thermal expansion coefficient and high thermal conductivity D epending on the degree of shape complexity required for specific applicatio ns, powders can be consolidated by either die compaction or powder injectio n molding The starting powder may be elemental Mo, which is infiltrated wit h Cu after pre-sintering, or it may consist of a blend of Mo and Cu powders , which are liquid phase sintered to near full density. The processing rout e selection is based mainly on shape complexity, but requires specific atte ntion to several processing parameters including particle size, green densi ty, and the thermal cycle. This work links these processing parameters with the resulting density microstructure, and thermal properties. Long sinteri ng times and controlled cooling rates ore needed for high density high ther mal conductivity heat sinks processed via liquid phase sintering, On the ot her hand thermal conductivities of 160 W/mK are achieved for Mo-15Cu throug h infiltration of either injection molded or die compacted Mo skeletons. Th e higher green densities available from die compaction enable pre-sintering of the Mo skeleton with shorter lower temperature thermal cycles. Furtherm ore, the pre-sintering and infiltration cycles con be combined into a singl e step Thus, infiltration of die compacted specimens is preferred except fo r the most complex heat sink geometries. For these cases injection molding is demonstrated as an alternate processing route.