Development of the Method for the Measurement of Single Crystal Elastic Constants from Polycrystalline Specimen

本研究的目的是制作一种用于在X射线衍射仪的圆盘形样品上施加双轴应力的致动器，并将其用于Hayakawa等人开发的从多晶样品确定单晶弹性常数的方法（J.Appl. Cryst.（1985）513-518）。TiNi形状记忆合金致动器的制作用TiNi合金制作了一个内径为18.5mm、外径为22.5-28.5mm、厚度为4 mm的环形致动器。时效处理使Ms温度低于0 ℃，Af高于室温。在Ms附近的温度下，通过插入具有较大直径的锥形棒来扩大环的内径。将盘形试样插入膨胀环中，同时保持温度低于Ms. A，随后将环和试样加热至高于Af并冷却至室温，使环达到初始形状，从而在插入的试样上施加双轴压缩应力。所施加的应力 ...更多信息 通过应变片测得的应变和杨氏模量得到了材料的应力，通过改变Ms和As温度、改变时效处理以及采用不同厚度的致动器，可以在室温下获得最高达250 MPa的不同应力水平.多晶单晶弹性常数的测定在多晶试样上施加几种不同的应力，由不同的反射得到d-间距，然后按上述方法直接计算单晶的弹性常数。对于Fe-35wt%Ni合金，测得C_<11>=1.249 ± <plus-minus>0.100，C_<12>=0.720 ± <plus-minus>0.073，C_<44>=1.219 ± <plus-minus>0.096 [10^5MPa]，与单晶Fe-30 Ni合金的C_<11>=1.463，C_<12>=0.881，C_<44>=1.132 [10^5MPa]相当。少

The aim of the present research was to make an actuator for exerting a biaxial stress on a disk shaped specimen for X-ray diffractometer and utilize it for a method to determine the single crystal elastic constants from a polycrystalline specimen which is developed by Hayakawa et al. (J.Appl.Cryst.. (1985) 513-518).1. Manufacturing of an actuator of TiNi shape memory alloyA ring shaped actuator (inner diameter 18.5mm, outer diameter 22.5-28.5mm, thickness 4mm) was made of TiNi alloy. A aging treatment brought the Ms temperature below 0ﾟC and Af above room temperature. At a temperature near Ms, the inner diameter of a ring was expanded by inserting a tapered rod with a larger diameter. A disk shaped specimen was inserted in the expanded ring while keeping the temperature below Ms. A subsequent heating the ring and specimen above Af and cooling to room temperature bring the ring to the initial shape, and thus exerts a biaxial compressive stress on the inserted specimen. The applied stres … More s was obtained by the strain measured through a strain gage pasted on the specimen and Young's modulus.Different level of stress up to 250MPa could be obtained at room temperature by modifying the Ms and As temperature by changing the aging treatment and by using different thickness of the actuator.2. Measurement of single crystal elastic constants from a polycrystalline specimenOnce a few different levels of stress were applied on a polycrystalline specimens and the d-spacings from various reflections were obtained, the calculation of the single crystal clastic constants were straightforward following the recipe presented by the above mentioned paper. For an Fe-35wt%Ni, the following values were obtained :C_<11>=1.249 <plus-minus> 0.100, C_<12>=0.720 <plus-minus> 0.073, C_<44>=1.219 <plus-minus> 0.096 [10^5MPa]The results compare well with the constants obtained for an Fe-30Ni alloy from a single crystal (C_<11>=1.463, C_<12>=0.881, C_<44>=1.132 [10^5MPa]).An application for a cubic zirconia is in progress. Less