Not that this might be worth anything, but a lot of recent CIP/apple patents refer to joining of BMG to aluminum or stainless steel....and other materials
It is irrelevant, at least this year. No BMG in any iPhones, two high end models will have stainless frame and the LCD will have aluminum frame. Li failed to land the phones. Only hope now is for the watch or something else (in smaller volumes). https://www.inverse.com/article/47696-apple-iphone-2018-3-stunning-features-coming