Diablo – Can Torment-only legendaries drop in Greater Rifts

From a blue post on the official Diablo 3 forum:

To clarify: Horadric Caches can drop any type of Legendary (regular or Bounty-exclusive) EXCEPT those that require Torment difficulty on higher. As difficulty has no impact on Horadric Caches, this also includes the ability to drop Torment-only Legendaries. Kadala is similar, as she also cannot generate Torment-only Legendaries.

Only the gear from monsters, including Rift Guardians, is affected by Difficulty level.

From the 2.0.5 patch notes:

Kadala - Can now drop Torment only Legendary items

Legendary crafting materials will only drop from the specific purple super-uniques. They will not drop from any other monster. Since none of the purple super-uniques ever show up in rifts, you cannot get them anywhere else.

The only legendary crafting mats that can drop in rifts are the ones not tied to super uniques, such as the Adventurer's Journal.