“…Generally, the origin of this fluid phase can be classified as being intrinsic or extrinsic to the reacting system itself. Intrinsic origins include melting (or contact melting) (Saratovkin and Savintcev, 1941;Gerasimov and Boldyrev, 1996;Urakaev and Boldyrev, 2000a;Boldyrev and Tkáčová, 2000;Chadwick et al, 2007;Michalchuk et al, 2014;Humphry-Baker et al, 2016;Fandiño et al, 2020;Haneef and Chadha, 2020), sublimation of solids (Kuroda et al, 2004;Mikhailenko et al, 2004), or dehydration/desolvation (Losev and Boldyreva, 2014) which result from the excess heating of mechanical impacts or bulk heating during mechanical treatment. Where a solids' glass transition temperature is above the milling temperature, one can consider also the formation of transient amorphous phases (Descamps and Willart, 2016a).…”