Influence of Zr addition on the microstructure, mechanical and electrical properties of Mo-Cu alloy

In order to strengthen the overall properties of Mo-Cu alloy, Zr was added to Mo-Cu alloy to enhance the bond strength of Mo/Cu interface and form solid solution strengthening effect. The excellent properties of Mo-Cu-Zr blocks were attained through infiltrating Cu-Zr blocks containing various Zr contents into the Mo skeleton. Compared to the incoherent interface of Mo/Cu in Mo-Cu block, the addition of Zr changed its interface to the coherent interface of Mo-Zr/Cu-Zr. All Mo-Cu-Zr alloy blocks possessed high densification degrees (97.1 %∼98.4 %) to assure the excellent general properties. Besides, the formations of Mo-Zr and Cu-Zr solid solutions assured the block owned excellent mechanical strength. Especially, the addition of Zr purified the grain boundary through absorbing oxygen to produce ZrO which prevented the Mo-Zr grain growth. As increasing Zr amount from 0 to 4.73 wt%, the Mo-Zr (or Mo) grain size reduced from 5 to 4.0 μm. Mo-Cu sintered sample containing 2.40 wt% Zr possessed the highest tension strength of 494 MPa. Besides, since the finer grain size of Mo-Zr alloy, this block also owned the highest micro-hardness (250 HV) and bending strength (1626 MPa), respectively. But, the generations of Cu-Zr solid-solution and ZrO also damaged the electrical conductivities to a certain extent. Specifically, as the addition amount of zirconium increased from 0 to 2.40 wt%, the conductivity decreased from 42.67 % to 32.15 %IACS.