Drag and drop the names of Ti phases:
Beta : [blank_start]........[blank_end]
If you cool fast enough from β (bcc), Ti will do a sudden diffusionless/martensitic transition (like steel does) but to a hexagonal phase called α’.
Drag and drop the names of the four broad classes of alloying elements for Ti:
• [blank_start]Alpha[blank_end] stabilisers – cumulative effect expressed as Al equivalent
• Isomorphous [blank_start]beta[blank_end] stabilisers
• Eutectoid beta stabilisers – cumulative effect of both kinds of beta stabilisers together is expressed as Mo equivalent
• Elements that don’t stabilise either phase more than the other but provide solid solution hardening (sticky places to hold dislocations etc, like in lecture 2) – these are Zr, Sn, Si.
Drag and drop the types of stabilising elements above each diagram:
Microstructure develops as [blank_start]α[blank_end] nucleates and grows on [blank_start]β[blank_end] grain boundaries and then grows in to take over the inside of the grain.
What you get depends strongly on two parameters:
• [blank_start]Grain[blank_end] [blank_start]size[blank_end] of the β before we started cooling (prior β grain size)
• [blank_start]Cooling[blank_end] [blank_start]rate[blank_end], both initially and after any heat treatments you do to it.
When we fracture Ti-alloy, the crack that will lead to its failure initiates on and propagates along the long bits of α on the grain boundaries