Foaming Behavior and Pore Structure Evolution of Foamed Aluminum under the Extrusion Constraint

Table 4

Possible mechanisms and their contribution to the volume gain/loss during foaming [23].

Foaming and expansion	Influencing factors
Volume gain (VG)	Gas expansion caused by hydrogen gas produced by TiH2 decomposition (HP)
	Gas expansion (GE) corresponded to the temperature rise of the sample (Ts)
Volume loss (VL)	Volume loss during the diffusion and overflow process of hydrogen gas (HD)
	Volume loss during the fracture of surface bubbles (BR)