Dependency of microstructure parameters and microhardness on the temperature gradient for directionally solidified Ti–49Al alloy

2011 ◽  
Vol 130 (3) ◽  
pp. 1232-1238 ◽  
Author(s):  
Jianglei Fan ◽  
Xinzhong Li ◽  
Yanqing Su ◽  
Ruirun Chen ◽  
Jingjie Guo ◽  
...  
Keyword(s):  
Temperature Gradient ◽  
Directionally Solidified ◽  
Microstructure Parameters

Morphological Characteristics of W-Nanowires after Selective Etching

2014 ◽  
Vol 1004-1005 ◽  
pp. 24-27
Author(s):  
Wen Jia Wang ◽  
Zhi Long Zhao ◽  
Ming Tang ◽  
Jian Jun Gao
Keyword(s):  
Growth Rate ◽  
Temperature Gradient ◽  
Directional Solidification ◽  
Morphological Characteristics ◽  
Selective Dissolution ◽  
Stability Diagram ◽  
Selective Etching ◽  
Directionally Solidified ◽  
Solidification Furnace ◽  
Nial Matrix

An eutectic NiAl–1.5 at.% W alloy prepared by using directionally solidified (DS)was employed as a source for producing W-nanowires. Several growth rate of 8,15,25/s was respectively used at a temperature gradient of ~240 K/cm in a Bridgman-type directional solidification furnace. A combined stability diagram was applied to predict proper conditions for the selective dissolution of NiAl matrix to get W-wires. Etching in a mixture of HCl:H2O2released parallel aligned W-nanowires with a wire diameter of ~500 nm. Different morphologies, such as nanobelts, lotus-shaped, conical of W-nanowires are obtained at the different conditions.

Microstructural Perturbations in Directionally Solidified Al-In, Al-Bi and Zn-Bi Monotectic Alloys

1981 ◽  
Vol 12 ◽  
Author(s):  
B. Toloui ◽  
A. J. Macleod ◽  
D. D. Double
Keyword(s):  
Melting Point ◽  
Temperature Gradient ◽  
Growth Velocity ◽  
Liquid Interface ◽  
Liquid Region ◽  
Directionally Solidified ◽  
Lower Melting Point ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Oscillatory Instabilities

ABSTRACTStudies have been made of the microstructures developed in directionally solidified monotectic Al-In, Al-Bi and Zn-Bi alloys, as a function of growth velocity and temperature gradient. With increasing growth velocity and decreasing gradient the microstructures show transitions from regular rod-like arrangements of the lower melting point phase, through arrays of aligned droplets to coarse irregular droplet dispersions. Intermediate stages show rods with longitudinal shape perturbations of a classic Rayleigh-type instability. The changes are discussed in terms of oscillatory instabilities at the solid-liquid interface (enhanced by increasing growth velocity and decreasing temperature gradient) coupled with ripening effects in the solid + liquid region behind the interface.

Effects of Growth Rates on Directionally Solidified Microstructure of Al-Ni-Y Ternary Alloy

2012 ◽  
Vol 562-564 ◽  
pp. 477-481
Author(s):  
Rui Xu
Keyword(s):  
Temperature Gradient ◽  
Directional Solidification ◽  
Ternary Alloy ◽  
Growth Rates ◽  
Optical Microscope ◽  
Experimental Results ◽  
Al Alloy ◽  
Directionally Solidified ◽  
X Ray Diffraction ◽  
X Ray

The directional solidification of the ternary Al alloy with composition of 2.6 at%Ni, 0.9 at%Y and 96.5 at% Al was carried out under the temperature gradient of 5 K/mm and the droping velocities of 0.5 mm/min, 1 mm/min, 5 mm/min, 10 mm/min, and 25 mm/min. The microstructure of the Al-Ni-Y ternary alloy was also analyzed by X-ray diffraction and optical microscope. The experimental results show that the microstructures of the Al-Ni-Y ternary alloy are consisted of ª-Al2, Al3Ni and Y4Ni6Al23phase when the alloy was directionally solidified in all directionally solidified rates in the experiments. No primary -Al can be found in the sample with directionally solidified rate of 0.5 mm/min. When the rates higher than 1 mm/min, the primary ª-Al can be observed. The microstructure of the directionally solidified alloy becomes finer and the primary ª-Al is smaller gradually with the increasing of growth velocities when the dropping rate of directional solidification is higher than 5 min/min. Two eutectic structures, Y4Ni6Al23andª-Al eutectic and Al3Ni and ª-Al eutectic, can be found when the dropping rate is higher than 10 mm/min.

Sign in / Sign up

Export Citation Format

Share Document