The substructures of martensite in a TiNiHf10 high temperature shape memory alloy

The martensite of a TiNiHf10 alloy has been determined to possess a monoclinic crystal lattice structure with lattice parameters of a = 0.289 nm, b = 0.408 nm, c = 0.468 nm and β = 98.9°. The (001) compound twins are found to be the substructures of the TiNiHf10 alloy and the [011] type II twin is found to be one kind of accommodation twin of the (001) twins. The (001) compound twin plane is parallel to the K1 plane of the [011] type II twins when they co-exist. Four spear-like martensite variants form a self-accommodation group by (011) type I twinning relationship.