Wei JIN
,
Mingzhou CAO
,
Rui YANG
,
Zhuangqi HU
,
Shaoyu QIU
,
Hong ZOU
材料科学技术（英文）
The effect of heat treatment on martensitic transformation behavior has been investigated in Ti44Ni47Nb9 alloy. The relation between transformation temperatures and critical stress of stress induced martensitic transformation is interpreted in terms of thermodynamic theory. It is shown that the decrease in transformation temperature in specimens of slow cooling rate or low temperature aging after solution heat treatment results from the changes of Ni/Ti ratio in the matrix. The increase of critical stress of stress induced martensitic transformation is a consequence of the decrease of transformation temperatures.
关键词:
Ti44Ni47Nb9 shape memory alloy
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Wei JIN
,
Ying YAN
,
Jian WANG
,
Mingzhou CAO
,
Rui YANG
材料科学技术（英文）
The mechanical behavior and the effect of pre-strain on recovery behavior of Ti50Ni47Fe3 (at. pct) alloy were investigated systematically by tensile and recovered tests accompanied by electrical resistance measurement. Ti50Ni47Fe3 alloy has different deformation behaviors at different temperature ranges, the deformation curves in different temperature range can be classified into four kinds. The start temperature of recovery increases with the increase of pre-strain. There exists an optimal deformation condition, at which the specimen exhibits maximum free recovery strain. With increasing pre-strain the recovery stress increases and reaches the maximum at 8% pre-strain. R-phase to parent transition offered about 0.2% recovery strain. With pre-strain increasing the recovery stress increases and reaches to the maximum at 8% pre-strain. The recovery stress is corresponding with the critical stress of stress-induced martensitic transformation.
关键词:
Deformation
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Xiaopeng LIU
,
Wei JIN
,
Mingzhou CAO
,
Dazhi YANG
,
Feixia CHEN
材料科学技术（英文）
Compared with the undeformed TiNi film, the martensite-austenite transformation (M-A) of the deformed one is elevated to a higher temperature on the first heating, but it nearly returns back to the original temperature on the second heating. An incomplete M-A transformation of the deformed TiNi film on the first heating divides the total martensite population into the self-accommodating martensite M2 and the oriented martensite M1. Thus, two transformations corresponding to M1-A and M2-A transition occur on the second heating. However, the forward transformation is not affected by the incomplete thermal cycle.
关键词:
TiNi film
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