If wall is thin (below 1mm), you can use a specialized Al solder.

Sn91Zn9 is the most common type. But you must insulate thermocouple first with enamel. This solution works up to 200C (depending on type of solder)

SiC or Al2O3-loaded silicone adhesive (like Nusil) is standard, simple, but lower-performing solution (works reliably up to 150C and has higher thermal resistance of contact).

Thanks Dr Nizhnik

Regards

Thermally conductive epoxy may be another option, such as Duralco 132 from Cotronics corporation.

Thanks Dr Chubarian and Dr Gurung

Regards