钛硅铝碳层间固溶体陶瓷的超结构现象

Superstructure Phenomenon in Ti_3Si_(y-x)Al_xC_z Interlayer Solid Solution Ceramics

研究了钛硅铝碳(Ti3Siy-xAlxCz)层间固溶体陶瓷材料的超结构现象。结果发现,用热压Ti、Si、Al和C(石墨)混合粉末原位反应合成的Ti3Si0.9Al0.3C1.93和Ti3Si0.8Al0.4C1.93层间固溶体块体样品的X射线衍射(XRD)谱中[00L]晶面的衍射峰极其微弱,只有[008]面有一个小的衍射峰,[002]、[004]和[006]面几乎没有衍射峰存在,而该块体样品的粉末的X射线衍射谱中所有[00L]晶面的衍射峰均存在。这种超结构现象表明,用热压原位反应合成的Ti3Si0.9Al0.3C1.93和Ti3Si0.8Al0.4C1.93实为层间无序固溶体。由于内应力的释放,取自该块体样品的粉末发生了从无序到有序的转变,所以粉末的X射线衍射谱中显现出强的[00L]面衍射峰。这种超结构相可能对Ti3Si0.9Al0.3C1.93和Ti3Si0.8Al0.4C1.93块体的性能产生重要影响。

The superstructure phenomenon in Ti3Siy-xAlxCz interlayer solid solution ceramics was found and studied. It is showed that in the X-ray diffraction patterns of the interlayer solid solution Ti3Si0.9Al0.3C1.93 and Ti3Si0.8Al0.4C1.93 bulk samples, which were in-situ reactively synthesized by hot-pressing the elemental Ti, Si, Al and C （graphite） mixed powders, the diffraction peaks of [00L] crystal planes are very weak, there is only a small diffraction peak belonging to the [008], and the diffraction peaks belonging to [002], [004] and [006] crystal planes almost not exist. However, all diffraction peaks belonging to [00L] crystal planes appear in the x-ray diffraction pattern of the powders taken from the bulk samples. This superstructure phenomenon demonstrates that the Ti3Si0.9Al0.3C1.93 and Ti3Si0.8Al0.4C1.93 bulk samples indeed are random solid solution. Due to the internal stresses releasing, the powders taken from the bulk samples generated a transition from random state to order, consequently the x-ray diffraction patterns of the powders presented stronger [00L] crystal plane diffraction peaks. This superstructure phase-change may take some fundamental effects on performances of the Ti3Si0.9Al0.3C1.93 and Ti3Si0.8Al0.4C1.93 bulk materials.