AlCoCrFeNi-NiTi high entropy alloy composites: Microstructure and wear performance

In the current research, AlCoCrFeNi-x wt% NiTi (x = 0, 5, and 10) high entropy alloy (HEA) composites were prepared using a combination of mechanical alloying and spark plasma sintering methods. Microstructural studies showed that the introduction of 5 wt% NiTi slightly changed the BCC and FCC fractions of the HEA matrix. However, in the HEA-10NiTi sample, which exhibited increase in the interfacial regions and acceleration of interdiffusion between elements, the (Ni,Al)-rich BCC phase fraction was considerably reduced. According to nano-indentation tests, the NiTi and BCC phases possess higher hardness-to-elastic modulus values that confirm the positive effect of these two phases on tribological behavior. Among the prepared specimens, HEA-5NiTi had the lowest wear rate (0.71 +/- 0.01 mm3/N center dot m). This is attributable to the higher BCC phase fraction and reinforcing effect of the NiTi particles.

Automated summary

AlCoCrFeNi-x wt% NiTi (x = 0, 5, and 10) high entropy alloy (HEA) composites were prepared using mechanical alloying and spark plasma sintering methods. The introduction of 5 wt% NiTi slightly changed the BCC and FCC fractions of the HEA matrix. However, in the HEA-10NiTi sample, there was a reduction in the (Ni,Al)-rich BCC phase fraction due to increased interfacial regions and accelerated interdiffusion between elements. Nano-indentation tests showed that the NiTi and BCC phases had higher hardness-to-elastic modulus values, indicating a positive effect on tribological behavior. HEA-5NiTi had the lowest wear rate among the prepared specimens, attributed to the higher BCC phase fraction and reinforcing effect of the NiTi particles.