Fabrication of TiNi Powder by Mechanical Alloying and Shape Memory Characteristics of the Sintered Alloy

Abstract

This paper presents the fabrication condition of TiNi alloy powder by mechanical alloying and shape memory characteristics of the sintered alloy. The effect of mechanical alloying condition on the characteristics of mechanically alloyed powder (MA powder) was investigated. Also, the difference in sintering behavior between the MA powder and the elementally mixed powders by V-blender and the shape memory characteristics of the sintered alloys were also examined. The MA powder was fabricated by milling using a planetary ball mill in a rotational speed between 200 and 500 min À1 for various milling times in an atmosphere of Ar gas. These two types of powders prepared in different processes were sintered using a pulse-current pressure sintering equipment at various sintering temperatures. The powder agglomerated and its particle size became larger with an increase in milling time. The mixture of Ti and Ni powders changed into an amorphous state by processing for 3.6 ks over 300 min À1 . The sintered alloy of the MA powder showed more uniform phase of TiNi than that of the elementally mixed powders sintered in a same manner, however, the former showed a lower density than the latter due to a larger particle size of the MA powder of before-sintering. It was found from the measurement of the transformation temperature of the sintered alloy of the MA powder using DSC that the alloy has shape memory characteristics, and the transformation temperatures of the alloy are higher than those of the alloy of the elementally mixed powders due to waste of Ni powder.

Fabrication of Ti-Ni-Zr Shape Memory Alloy by P/M Process

“…[6][7][8] Using a mechanically alloyed (MAed) powder has an advantage in homogeneous microstructure of the sintered alloy, 9) moreover, MA is a favorable process for refinement of grain size in sintered Ti-Ni-Zr alloy.…”

Single walled carbon nanotubes reinforced intermetallic TiNi matrix nanocomposites by spark plasma sintering

“…A pulse current pressure sintering equipment was used for the consolidation at various sintering temperatures of TiNi alloy powder prepared by mechanical alloying [8]. A bulk Ni-Timaterial with refined microstructure was obtained by spark plasma sintering (SPS) starting from amorphous mechanically alloyed NiTi powders [9].It has also been made to develop TiNi matrix composites to further increase the wear resistance. The reinforcing phases include TiC [10], TiN [11] and precipitated Ti 2 Ni [12], it is considered that the hard reinforcing phases can be used to sustain external load, while the TiNi matrix may accommodate deformation, absorb impact energy and retain hard particles.…”

Single Walled Carbon Nanotubes Reinforced Intermetallic TiNi Matrix Nanocomposites by Spark Plasma Sintering

“…A pulse current pressure sintering equipment was used for the consolidation at various sintering temperatures of TiNi alloy powder prepared by mechanical alloying [8]. A bulk Ni-Ti material with refined microstructure was obtained by spark plasma sintering (SPS) starting from amorphous mechanically alloyed NiTi powders [9].It has also been made to develop TiNi matrix composites to further increase the wear resistance. The reinforcing phases include TiC [10], TiN [11] and precipitated Ti 2 Ni [12], it is considered that the hard reinforcing phases can be used to sustain external load, while the TiNi matrix may accommodate deformation, absorb impact energy and retain hard particles.…”