Ownership in this 165-family corpus is fragmented rather than concentrated under one dominant company. The clearest collaboration signal is between named individual inventors, with Oishi Yukihiro and Kawabe Nozomu sharing 7 families and two further pairings each sharing 5. Organisations such as Sumitomo Electric Industries appear with representative filings, but no single assignee holds a commanding share of the ranking, which favours a competitive rather than blocked field for new entrants.

Filing activity peaked at 7 families in 2018 and has not returned to that level since, with the 2022 midpoint sitting at 4. That is a flat-to-declining curve across the 2015-2026 window covered here, not sustained growth. Because publication lags filing by roughly 18 months, the final one to two years in the data will understate true activity, so the apparent recent slowdown should be treated cautiously rather than read as a hard stop.

Alloy composition (IPC class C22C) and metal casting (B22D) carry the bulk of the filing activity, appearing in 141 and 81 of the 165 records respectively. Thermal treatment of non-ferrous metals (C22F) is also well represented. Rolling, extrusion and powder metallurgy each show meaningfully fewer records, which signals where the claim space is thinner rather than where the technology is necessarily less mature.

The clearest gaps sit in extrusion scale-up and powder metallurgy consolidation, each covered by roughly a tenth of the record count seen in alloy composition claims, despite both appearing directly in the search terms. Twin-roll casting process control and continuous coiling thermal profiles are narrower branches within the casting and rolling classes that also show thinner coverage relative to the core alloy space. These are starting points for a freedom-to-operate search, not a guarantee that no relevant prior art exists.

US9604267B2, assigned to Sumitomo Electric Industries and published in 2017, claims a continuous process for producing magnesium alloy coil stock: preheating a raw sheet to 280°C or less, rolling it with a reduction roll held between 230°C and 290°C, and repeating the preheat-roll-coil cycle continuously. It constrains that specific temperature window and continuous-cycle approach for coil production, but it does not cover magnesium processing generally. A process using a different temperature range, a batch rather than continuous cycle, or a different forming method would need its own freedom-to-operate review rather than relying on this one patent as a blanket block.