Hf 含量对 CoCrFeNiHf_x共晶高熵合金显微组织与摩擦性能的影响

A series of CoCrFeNiHf_x (x=0.3, 0.43 and 0.5) eutectic high entropy alloys with different Hf contents were designed, and the effects of Hf content on the microstructure, microhardness and tribological properties of CoCrFeNiHf_x eutectic high entropy alloys were investigated. With the increase of Hf content, the as-cast microstructures change from hypoeutectic (primary γ phase+ γ/Laves eutectic phases, x=0.3) to eutectic (γ/Laves eutectic phases, x=0.43) and hypereutectic (primary Laves phase+ γ/Laves eutectic phases, x=0.5). With the increase of Hf content, the microhardness of alloy increases and the friction coefficient remained almost does not change. The results of nanoindentation show that the hardness of both primary phase and eutectic phases in experimental alloys increase with the increase of Hf content. Meanwhile, the wear depth firstly decreases and then increases, and the wear mechanism changes from adhesive wear to abrasive wear. CoCrFeNiHf_0.43 alloy shows the best wear resistance, which is caused by lamellar eutectic phases underwent synergistic deformation during wear process, and thus CoCrFeNiHf_0.43 alloy is not prone to occur brittle spalling during wear.