Experimental and Numerical Investigations on Interdiffusion Profiles in Compounds Produced by Sinter-Cladding
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MINERAL processing applications suffer from coarse abrasive wear and high dynamic loads. Therefore, tools for mineral processing applications have to fulfill the requirements of a high hardness and high fracture toughness at the same time. These opposing requirements can be achieved using a composite tool concept with a wear-resistant cladding and a tough substrate material. Common fabrication processes to apply such claddings are composite casting,[1–3] deposit welding,[4] and HIP cladding.[5] An alternative process to HIP cladding for the production of powder-metallurgical compound materials is sinter-cladding, which uses the principles of supersolidus liquid phase sintering (SLPS) for the compaction and application of high-alloyed cold work tool steels[6] to low-alloyed steel substrates. Figure 1
M. BLU¨M and S. WEBER are with the Lehrstuhl fu¨r Neue Fertigungstechnologien und Werkstoffe, Fakulta¨t fu¨r Maschinenbau und Sicherheitstechnik, Bergische Universita¨t Wuppertal, 42651, Solingen, Germany. Contact e-mail: [email protected] W. THEISEN is with the Lehrstuhl Werkstofftechnik, Institut fu¨r Werkstoffe, Ruhr-Universita¨t Bochum, 44780, Bochum, Germany. Manuscript submitted February 7, 2018.
METALLURGICAL AND MATERIALS TRANSACTIONS A
shows a schematic sketch of the process. The powder-metallurgical cladding material is placed inside a crucible and the substrate material is put on top of this metal-powder. Usually, prealloyed gas-atomized powders with a particle size of 36 lm < d50 < 100 lm are used. At sintering temperature, which is above the solidus temperature, the cladding material is densified by supersolidus liquid phase sintering and the substrate sinks into this semisolid material. A schematic drawing of the compaction model of SLPS is given in Figure 2. It shows that below the solidus temperature solid-state sintering as described by Frenkel[7] occurs. However, above the solidus temperature the liquid phase forms within the prealloyed powder particles by melting of low melting phases within the alloy.[8] For the compaction of cold work tool steels via SLPS, a minimum liquid phase content of 10 vol.pct is needed.[9] At this state, the powder particles disintegrate due to sliding effects along the wetted grain boundaries and the cladding material is compacted due to capillary forces.[10] In case of sinter-cladding, the liquid phase also wets the interface between the substrate and the semisolid cladding resulting in a diffusional bond. Former investigations on supersolidus-sintered compounds have proven the feasibility of sinter-cladding[6] but have also shown that the ideal sintering temperature of the compound differs from the ideal sintering temperature of the cladding material. As can be seen
on the tool’s mechanical properties at the interface.[12] Therefore, a prediction of the diffusion processes within a compound material is of major interest to optimize the manufacturing and heat treatment of the compounds. Several investigations related to diffusion within solids proved that diffusion calcula
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