Determination of Relation between Elastic Constant and Si ntered Temperature in WC-Ni Composites
In this study we have investigated relation between elasti c constant and sintered temperature in tungsten carbide- nickel composite samples. Determination of elastic properties of materials is based on the transverse and longitudinal wave’s velocities via ultrasonic methods. In this study ultrasonic velocity measurements were measured in the WC-Ni composites. These samples are formed by powder metallurgy and electroless plating. Samples were sintered at temperat ures of 1000 °C, 1100 °C, 1200 °C and 1300 °C with Ar gas atmosphere in tube furnace. In the measuring ultrasonic longitudinal velocity 2 and 5 MHz transducers, ultrasonic transverse velocity 1 and 5MHz transducers have been used. Young Modulus (E) has been calculated by using longitudinal and transverse velocity. A fter we calculated elastic constant, we have investigated relation between sinter ed temperature and elastic constant of samples. A linear relation between sinter ed temperature and elastic constant in samples is observed.
Measurement of elastic constants by the ultrasonic pulse method
Definitions of stress and strain are given in terms of force and differential coefficients of displacement respectively and the generalized form of Hooke's law stated. This defines the elastic constants of a general aeolotropic medium. Special cases of cubic and hexagonal symmetry are considered. The elastic wave equations are derived for plane waves in an infinite aeolotropic solid. The velocities of the three types of wave are given for certain directions in cubic and hexagonal materials. Difficulties may be encountered in propagation of waves along axes other than principal ones due to the oblique path along which the energy travels. This may limit the use of the method to certain directions depending upon the geometry of the specimen. A brief outline of the apparatus used is given and the accuracy which may be achieved is discussed. The method may be applied to polycrystalline materials provided that the grain size is reasonably small.
Geomagnetic Polarity Epochs: Sierra Nevada Data, 3
Available paleomagnetic and radiometric results for about 60 igneous rocks 3.6 m.y. old or less are consistent with the following geomagnetic polarity epoch time scale: Brunhes normal polarity epoch, 0.0 to 0.85±0.15 million years; Matuyama reversed polarity epoch, 0.85±0.15 to 2.4±0.1 million years; Gauss normal polarity epoch, 2.4±0.1 to 3.35±0.1 million years; Gilbert reversed polarity epoch, 3.35±0.1 million years to (?). A brief interval of normal polarity (the Olduvai event) occurs within the Matuyama reversed epoch at about 1.9 m.y., and a brief interval of reversed polarity (the Mammoth event) occurs within the Gauss normal epoch at about 3.06 m.y. Data for twelve units from eastern California and Nevada, reported here for the first time, are particularly useful in defining the Gauss-Gilbert boundary and for recognizing the Mammoth event.