Effect Of Heat Treatment On The Friction And Wear Behavior Of A ZrTiAlV Alloy

In this stduy, a domestic newly developed high specific strength 47Zr45Ti5Al3-V alloy was selected as the experimental material. After processing various heat treatment on the alloy, the friction and wear tests were carried out in air at room temperature and in vacuum at cryogenic temperature by using a special friction and wear equipment. The microsturcuture features, mechincal porpeties as well as friction and wear behaviors of the examined 47Zr45Ti5Al3 V alloy were carefully investigated by using metallographic microscope, x-ray diffraction(XRD), transmission electron microscope(TEM), universal material test system, nano-indentation machine, micro-hardness tester and scanning electron microscope(SEM).XRD analysis reuslts reveal that the annealed 47Zr45Ti5Al3 V alloy is mainly composed of α and β phases, with the lamellar α phase precipitating from the interior of β grain and forming a basketweave struture.The thickness of α phase increases with rising annealing temperature. After normolizing at 600?C or 700?C, respectively, the 47Zr45Ti5Al3 V alloy is composed of α phase and β phase, and a new phase, ? phase was found in the 600?C normolized sample, which makes the alloy harder than others.The thickness of α phase precipitating from β is extremely thin, nearly invisible as eamied by metallographic microscope. The 800?C normolized 47Zr45Ti5Al3 V alloy is only composed of β phase, resulting in the lowest hardness. After quenching from the two phase zone, the alloy is mainly composed of α phase and β phase with no other metastable phase, and the precipitatded α phase is very fine. The 900?C quenched alloy is mainly composed of β phase and a small amount of α? martensite which precipitated during quenching process. There is a large number of lamellar α phase precipitating from β phase in the quenched sample after aging, which is helpful to improve mechanical properties of the 47Zr45Ti5Al3 V alloy.The friction and wear test results show that the 47Zr45Ti5Al3 V alloy, which obtained higher hardness or single β phase microstructure after heat treatmnet, would exhibit more excellent wear resistance. The wear morphology SEM observation and EDS analysis reuslts indicate that the main wear mechanism of the various heat treated 47Zr45Ti5Al3 V alloy samples is abrasive wear and adhesive wear either in air at room temperature or in vacuum at cryogenic temperature. The abrasive wear features can be identified as furrow and groove formed by extrusion of hard surface micro convex-body, and microcarck, lamellar wear particles and large concave induced by fatigue peeling wear. The former is mainly affected by the hardness of the alloy, the latter is controlled by balance of strength and plasticity of the alloy. The adhesive wear is characterised by small peeling pit, which is thought to be affected by stength of the alloy. The current friction and wear test results imply that the wear of the 47Zr45Ti5Al3 V alloy is greatly influenced by peeling wear, and the single-phase microstructure seem to be effective in reducing fatigue peeling wear and thus improving the wear resistance of the alloy.