固溶时效态Ti-Ni合金相变行为与Ni含量的关系

RELATIONSHIP BETWEEN TRANSFORMATION BEHAVIORS AND Ni CONTENT IN SOLUTION-AGED Ti-Ni ALLOYS

固溶淬火态Ti_(100-x)Ni_x合金中,x=40.0—49.0时,合金的马氏体相变(MT)温度(T_M)、热滞(△T_M)不变,相变热(△H_M)升高;x=49.0—52.0时,合金的T_M和△H_M急剧下降,△T_M急剧升高;x=52.0—56.0时,合金的T_M和△H_M升高,△T_M降低;x=56.0—70.0时,合金的T_M和△T_M变化不大,△H_M下降,673 K时效态 Ti_(100-x)Ni_x合金中,x=40.0—50.0时,合金发生MT,不存在时效效应;x=50.5—70.0时,合金既发生MT又发生R相相变(RT)且具有时效效应,随时效时间(t_A)延长,T_M和△H_M先下降后上升,△T_M下降,T_R随x增加保持不变,随t_A延长而升高,△T_R对x和t_A不敏感,△H_R对x和t_A都十分敏感,x=40.0—50.0和x=50.5—70.0合金的室温组织分别为M+TiNi_2和A(母相)+析出物,随x增加或t_A延长,x=50.5—70.0的合金中析出物数量增多。

For the solutionquenched Ti100-xNix alloys, when x = 40.0-49.0, the martensitic transformation (MT) temperature (T-M) and temperature hysteresis (DeltaT(M)) of alloys are constant, and the MT heat (DeltaH(M)) of alloys increases with in creasing x; when x = 49.0-52.0, the T-M and DeltaH(M) decrease, and the DeltaT(M) increases drastically; when x = 52.0-56.0, the T-M and DeltaH(M) increase, and the DeltaT(M) decreases; when x = 56.0-70.0, the T-M and DeltaT(M) are nearly of no change, and the DeltaH(M) decreases. When x = 40.0-50.0 for the 673 K aged Ti100-xNix alloys, the MT occurs in alloys which have no aging effects; when x = 50.5-70.0, the MT and the R phase transformation occur in alloys which have aging effects. The T-M and DeltaH(M) decrease first and then increase, and DeltaT(M) decreases with increasing aging time (t(A)). The T-R is not sensitive to x, but sensitive to t(A). The T-R is constant with increasing x, and increases with increasing t(A). The DeltaT(R) is constant and not sensitive to x and t(A). The DeltaH(R) is extremely sensitive to x and t(A). When x=40.0-50.0 and x = 50.5-70.0, the room temperature microstructures of Ti-Ni alloys are M with TiNi2, and A (parent phase) with precipitates, respectively. When x = 50.5-70.0, the volume fractions of precipitates in Ti-Ni alloys increase with increasing x or t(A).