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Page 20 of 45 Mooraj et al. J Mater Inf 2023;3:4 https://dx.doi.org/10.20517/jmi.2022.41

Figure 9. (A) Fractions of CALPHAD predicted single-phase solid solution, intermetallics, and solid solution and intermetallic
equimolar alloys in 3 to 6 component alloy systems at the melting temperature (T ) and at 600 °C. This figure is quoted with
m
[130]
permission from Senkov et al. ; (B) two-dimensional projection of Al Cr Mo Nb Ti V phase diagram from CALPHAD
a b c d e 1-a-b-c-d-e
showing compositions within two-dimensional space where a BCC solid solution phase forms at 800K. This figure is quoted with
[131]
permission from Klaver et al. . IM: Intermetallic; SS: solid solution.
models are the best methods to screen through the massive composition space. However, the experimental
databases on this system lack size and detail, and thus a ML approach cannot be adequately trained. For this
reason, Conway et al. used high throughput CALPHAD methods to design composition within the Cantor
alloy system (Co-Cr-Fe-Ni-Mn) that possesses a combination of high SPSS stability, good mechanical
properties, and low material cost . The high-throughput screening analyzed 1.78 million compositions
[135]
where the elemental contents were gradually incremented by 1-2 at. % interval step. The phase fractions
were calculated every 50 K between 500 K to 2,500 K to screen for compositions that produced thermally
stable SPSS. Further constraints were applied to ensure every element was present in at least 10 at. %, and
the Co and Ni contents were limited to 15 and 20 at. % to reduce the cost of the alloys. Twinning-induced
plasticity (TWIP) and solid solution hardening (SSH) were fundamental strengthening mechanisms within
this system. Thus, the authors used parameters within the TC-HEA database for their CALPHAD
calculations of the SSH values and stacking fault energies (SFEs) for the screened compositions. Figure 10A
shows the SFE and SSH plots in a quaternary diagram where the Co content was assumed constant at 10
at. %. The red circle illustrates the composition chosen by the authors (Co Cr Fe Mn Ni ), while the red
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stars indicate the optimal composition using only the SFE or SSH as the guiding parameter. The
composition explored showed only slightly lower yield strength than the equiatomic Cantor alloy at room
temperature but showed high strength and ductility at elevated temperatures and exhibited a 40% reduction
in cost compared to the equiatomic Cantor alloy. Based on these results, future thermodynamic screening
for alloys can incorporate the strengthening mechanisms and material cost into complex alloy design.
The process-structure-property-performance (PSPP) relationship is the central paradigm in materials
science. The fundamental goal of many materials scientists is to use computation, theory and
experimentation to establish causal trends between the individual elements of PSPP to systematically
achieve better material performance. To that end, Abu-Odeh et al. contextualized alloy design as an inverse
phase stability problem (IPSP) . IPSP is defined as the need to identify the set of thermodynamic
[136]