Which metals are characterized by pseudo-elasticity and shape memory effects?

The characteristic of pseudo-elasticity and shape memory effects is primarily associated with certain alloys, particularly shape memory alloys (SMAs), such as nickel-titanium (NiTi). These alloys demonstrate unique properties where they can return to a predetermined shape when subjected to specific thermal conditions.

The term "rearrangement of molecules" is relevant here because the phase transformation that enables shape memory effects involves the transition between different atomic arrangements. When heated above a certain temperature, the alloy changes from a low-temperature phase (martensite) to a high-temperature phase (austenite), allowing it to "remember" and adopt its original shape.

In contrast, the other options do not succinctly define this phenomenon. For instance, while ferromagnetic materials may exhibit interesting magnetic properties, they do not inherently have pseudo-elasticity or shape memory effects. The references to alloy metals with high thermal conductivity or low melting points do not capture the essential aspect of molecular rearrangement that is crucial for these unique physical properties. Therefore, the focus on molecular rearrangement directly connects to the mechanisms behind pseudo-elasticity and shape memory effects, making it the most accurate choice.