Effect of Equal-Channel Angular Pressing on the Microstructure and Superelastic Behavior of Ti-25 at. % Nb Shape Memory Alloy

2010 ◽  
Vol 667-669 ◽  
pp. 1071-1076
Author(s):  
Jie Song ◽  
Xiao Ning Zhang ◽  
Xiao Gang Sun ◽  
Chao Ying Xie

Microstructure and mechanical behavior of Ti-25 at. % Nb shape memory alloy processed by equal-channel angular pressing (ECAP) at 673 K have been investigated. The effect of multi-passes ECAP on the martensitic transformation temperature and superelastic recovery strain of Ti-26 at. %Nb alloy have been analyzed. It is found that the Ti-25 at. % Nb alloy exhibits superelasticity with a recovery strain of 1.6 % after one pass ECAP process. As the ECAP pass numbers increases to four passes, the superelasticity increases a little. The yielding stress (σ0.2) of Ti-25 at. % Nb alloy increases to 430 MPa and the ultimate tensile strength (UTS) is near 678 MPa after one pass ECAP process at 673 K, but the yielding stress and ultimate tensile strength increases little after four pass ECAP. The grain size decreases sharply from 100 μm to no more than 500 nm after four passes ECAP process. Effect of ECAP on the microstructure evolution and Young's modulus has been analyzed.

2006 ◽  
Vol 114 ◽  
pp. 91-96 ◽  
Author(s):  
Maxim Yu. Murashkin ◽  
M.V. Markushev ◽  
Julia Ivanisenko ◽  
Ruslan Valiev

The effects of equal channel angular pressing (ECAP), further heat treatment and rolling on the structure and room temperature mechanical properties of the commercial aluminum alloys 6061 (Al-0.9Mg-0.7Si) and 1560 (Al-6.5Mg-0.6Mn) were investigated. It has been shown that the strength of the alloys after ECAP is higher than that achieved after conventional processing. Prior ECAP solution treatment and post-ECAP ageing can additionally increase the strength of the 6061 alloy. Under optimal ageing conditions a yield strength (YS) of 434 MPa and am ultimate tensile strength (UTS) of 470 MPa were obtained for the alloy. Additional cold rolling leads to a YS and UTS of 475 and 500 MPa with 8% elongation. It was found that the post-ECAP isothermal rolling of the 1560 alloy resulted in the formation of a nano-fibred structure and a tensile strength (YS = 540 MPa and UTS = 635 MPa) that has never previously been observed in commercial non-heat treatable alloys.


2009 ◽  
Vol 63 (30) ◽  
pp. 2676-2679 ◽  
Author(s):  
Ping Zhang ◽  
Aibin Ma ◽  
Sheng Lu ◽  
Pinghua Lin ◽  
Jinghua Jiang ◽  
...  

2011 ◽  
Vol 682 ◽  
pp. 49-54
Author(s):  
Bin Chen ◽  
Chen Lu ◽  
Dong Liang Lin ◽  
Xiao Qin Zeng

The Mg96Y3Zn1 alloy processed by equal channel angular pressing has been investigated. It was found that the Mg96Y3Zn1 alloy processed by ECAP obtained ultrafine grains and exhibits excellent mechanical properties. After ECAP, the average grain size of Mg96Y3Zn1 alloy refined to about 400 nm. The highest strengths with yield strength of 381.45MPa and ultimate tensile strength of 438.33MPa were obtained after 2 passes at 623K. It was found that cracks were preferentially initiated and propagated in the interior of X-phase during the tensile test. As a result, the elongation of alloy is decreased with pass number increasing.


2013 ◽  
Vol 690-693 ◽  
pp. 3-7
Author(s):  
Yuan Zhi Huang ◽  
Shi Qiang Lu ◽  
Jun Wei Liu ◽  
Ke Lu Wang ◽  
Gui Fa Li ◽  
...  

The effect of annealing temperature(300-600°C)on the microstructure and transformation temperature of NiTiNb shape memory alloy rods deformed with equal channel angular pressing(ECAP) method was analyzed. The results show that the hard brittle phase (Ti,Nb)2Ni was decreased after ECAP. With the rising of annealing temperature, the number of β-Nb phase increase while eutectic declines. The DSC analysis shows that the martensite and reverse transformation temperature increase with annealing temperature. After annealing with 500°C, the martensite/austenite transformation starting temperatures rise to -64.6°C and -30.1°C, respectively.


2012 ◽  
Vol 629 ◽  
pp. 198-202 ◽  
Author(s):  
Ping Yang ◽  
Kai Huai Yang

Three groups of commercial 1050 Al alloy were subjected to equal channel angular pressing (ECAP) at room temperature using route A, route C and route Bc, respectively. Mechanical properties and fracture modes of as-annealed and ECAPed samples were investigated. The microhardness of 1050 Al fabricated by ECAP increases by a factor of about 1.5 compared to the as-annealed state. The ultimate tensile strength (UTS) increases significantly after ECAP, while the elongation decreases. But they are strongly dependence on the number of ECAP passes and the pressing route. The UTS and elongation of the samples processed by route Bc are best, consequently, the static toughness U of the samples is enhanced. Besides, all specimens subjected to ECAP deformation failed in a ductile manner.


2011 ◽  
Vol 194-196 ◽  
pp. 1720-1723 ◽  
Author(s):  
Li Ping Bian ◽  
Wei Liang ◽  
Wen Li Zhang

Microstructure and mechanical property of a hypoeutectic Al-Mg2Si composite processed by equal channel angular pressing up to eight passes in a combined route 2A+4BA+2A were investigated. The results show that the initial developed eutectic Mg2Si was significantly refined into submicrometer-scale particles and distributed homogeneously in the Al matrix, which together with the refinement of Al matrix leads to a much higher ductility with the elongation to failure up to 24% and a significantly enhanced ultimate tensile strength of 284MPa in the processed composite, increased by 2300% and 70%, respectively, compared to those in its as-cast counterpart.


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