2Ni相；當(dāng)V 含量大于0.5at%時(shí)，NiTiV形狀記憶合金形成B19'相、Ti2Ni相和V的富集相，并且隨著V含量增加，V的富集相越來(lái)越多聚集于晶界。進(jìn)一步分析表明，Ni49.75Ti49.75V0.5和Ni49.25Ti49.25V1.5 形狀記憶合金發(fā)生了B2?B19'的一級(jí)相變，而Ni48.75Ti48.75V2.5和Ni48.25Ti48.25V3.5形狀記憶合金發(fā)生了B2?R?B19'的二級(jí)相變，盡管降溫過(guò)程中同時(shí)發(fā)生了部分的R相變與B19'馬氏體相變。隨著V含量增加，相變溫度隨著V含量增加逐漸降低，其主要原因是Ni/Ti比例的增加。此外，隨著V含量增加，合金的顯微硬度值呈現(xiàn)先降低然后幾乎保持不變的變化規(guī)律。;The effect of vanadium (V) content on the microstructure, phase transformation behavior, and microhardness of the as-cast equiatomic NiTi shape memory alloy was investigated by optical microscope (OM), scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and Vickers microhardness tester. Results indicate that the as-cast Ni50-x/2Ti50-x/2Vx alloys with equiaxed grains consist mainly of B19' and Ti2Ni phases when V content is 0.5at%, above which Ni50-x/2Ti50-x/2Vx (x=1.5~3.5, at%) alloys exhibit a three-phase structure consisting of B19', Ti2Ni and V-rich phases, and the V-rich phases are more segregated at grain boundaries with the increase of V content. Further analysis reveals that both Ni49.75Ti49.75V0.5 and Ni49.25Ti49.25V1.5 alloys show a one-stage B2?B19' transformation. However, a two-stage B2?R?B19' transformation occurs in Ni48.75Ti48.75V2.5 and Ni48.25Ti48.25V3.5 alloys although R-phase transformation partially overlaps B19' martensitic transformation upon cooling. The transformation temperatures drop down with increasing the V content, which is attributed to the increase of Ni/Ti ratio in the matrix. In addition, as V element increases from 0.5at% to 3.5at%, the microhardness of the alloys first decreases and then remains almost unchanged."/>