Excellent strength-ductility combination of multi-layered sheets composed of high-strength V10Cr10Fe50Co30 high entropy alloy and 304 austenitic stainless steel

초록

When a high-entropy alloy (HEA) and an austenitic stainless steel (STS) are combined to produce a multi-layered sheet (MLS), the synergic effects of maximized body-centered-cubic(BCC) transformation-induced plasticity (TRIP) occurring in both HEA and STS on excellent tensile properties are expected. In this study, the tensile properties of STS/HEA/STS MLS, fabricated by hot-roll bonding, were compared with those of monolithic HEA and STS sheets. Both the HEA and STS layers of the MLS consisted of FCC grains, while some BCC grains occurred mostly in the HEA layer. The measured tensile properties were higher than the calculated values based on the rule of mixtures, and showed very high levels of tensile strength (803 and 1774 MPa at 25 degrees C and -196 degrees C, respectively) with sufficient elongation (44% and 72%, respectively). This result was attributed to the robust TRIP mechanism occurring step-by-step in the HEA and STS layers, along with the accommodation of the strain gradient near the strongly bonded HEA/STS interface. The step-by-step TRIP played a leading role in tuning the enormous BCC-TRIP occurring in both the HEA and STS layers, while taking complete advantage of the high strength-ductility balance.

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