Unidirectional Solidification of a Nbss/Nb5Si3 In-Situ Composite

2005 ◽  
Vol 475-479 ◽  
pp. 745-748 ◽  
Author(s):  
X.P. Guo ◽  
Ping Guan ◽  
X. Ding ◽  
Jun Zhang ◽  
K. Kusabiraki ◽  
...  
Keyword(s):  
Room Temperature ◽  
Melting Furnace ◽  
Longitudinal Axis ◽  
Zone Melting ◽  
Tensile Fracture ◽  
Al Alloy ◽  
Floating Zone ◽  
Directionally Solidified ◽  
In Situ Composite

The directionally solidified specimens of Nb-13.52 Si-22.60 Ti–6.88 Hf–2.54 Cr–2.24 Al alloy were prepared in an electron beam floating zone melting furnace at the withdrawing rate of 0.1, 0.3, 0.6, 1.0, 2.4 and 6.0 mm/min. All the primary Nb solid solution (Nbss) columns, Nbss + (Nb)3Si/(Nb)5Si3 eutectic colonies and divorced (Nb)3Si/(Nb)5Si3 plates or chains align well along the longitudinal axis of the specimens. With increasing of the withdrawing rate, the microstructure is gradually refined, and the amount of Nbss + (Nb)3Si/(Nb)5Si3 eutectic colonies increases. Both the room temperature ultimate tensile strength σb and fracture toughness KQ are improved for the directionally solidified specimens. The tensile fracture occurs in a cleavage way.

Microstructure of Al2O3/YAG/ZrO2 Eutectic In Situ Composite Prepared by Laser Floating Zone Melting

2012 ◽  
pp. 217-224
Author(s):  
Kan Song ◽  
Jun Zhang ◽  
Xiaojiao Jia ◽  
Haijun Su ◽  
Lin Liu ◽  
...  
Keyword(s):  
Zone Melting ◽  
Floating Zone ◽  
In Situ Composite

Microstructure and Mechanical Properties of an Advanced Niobium Based Ultrahigh Temperature Alloy

2007 ◽  
Vol 539-543 ◽  
pp. 3690-3695 ◽  
Author(s):  
X.P. Guo ◽  
L.M. Gao ◽  
Ping Guan ◽  
K. Kusabiraki ◽  
Heng Zhi Fu
Keyword(s):  
Mechanical Properties ◽  
Electron Beam ◽  
Directional Solidification ◽  
Room Temperature ◽  
Zone Melting ◽  
Floating Zone ◽  
Directionally Solidified ◽  
Microstructure And Mechanical Properties ◽  
Temperature Fracture ◽  
Ultrahigh Temperature

The microstructure and mechanical properties including room temperature fracture toughness Kq, tensile strengthσb and elongationδ at 1250°C of the Nb based alloy directionally solidified in an electron beam floating zone melting (EBFZM) furnace have been evaluated. The microstructure is primarily composed of Nb solid solution (Nbss), α-(Nb)5Si3 and (Nb)3Si phases. After directional solidification with the moving rate of electron beam gun R being respectively 2.4, 4.8 and 7.2 mm/min, the primary Nbss dendrites, Nbss + (Nb)5Si3/(Nb)3Si eutectic colonies (lamellar or rod-like) and divorced Nb silicide plates align along the longitudinal axes of the specimens. When R = 2.4 mm/min, the best directional microstructure is obtained. Directional solidification has significantly improved theσb at 1250°C and Kq. The maximumσb occurs for the specimens with R = 2.4 mm/min and is about 85.0 MPa, meanwhile, the Kq is about 19.4 MPam1/2.

Microstructure and Mechanical Property of Al2O3/Y3Al5O12 (YAG) Eutectic Ceramic In Situ Composite Prepared by Laser Zone Melting

2007 ◽  
Vol 561-565 ◽  
pp. 999-1002
Author(s):  
Hai Jun Su ◽  
Jun Zhang ◽  
Lin Liu ◽  
Heng Zhi Fu
Keyword(s):  
Mechanical Property ◽  
Processing Parameters ◽  
Zone Melting ◽  
Eutectic Microstructure ◽  
Processing Parameter ◽  
Directionally Solidified ◽  
In Situ Composite ◽  
Scanning Rate ◽  
Interface Phases

Directionally solidified Alumina-based eutectic ceramic in situ composite is a kind of promising candidate for high temperature structural material applied at elevated temperature above 1923K because of its excellent properties. With laser zone melting directional solidification, Al2O3/Y3Al5O12 (YAG) eutectic ceramics are successfully prepared. The relationship between the eutectic microstructure and the processing parameter is studied, and the mechanical property of the composite is measured. The results show that: (1) Laser power density and scanning rate strongly affect the eutectic microstructure. With proper processing parameters adjusted, the binary lamellar eutectic microstructure is obtained, in which Al2O3 and YAG phases are three-dimensionally coupled and continuously connected without grain boundaries and amorphous interface phases. (2) The eutectic spacing decreases to about 1μm with increasing scanning rate. (3) The maximum hardness of 19.5GPa and the room fracture toughness of 3.6MPa.m1/2 are obtained by Vickers indentation measurement.

Dry sliding wear behaviour of AA 6351-ZrB2 in situ composite at room temperature

2010 ◽  
Vol 31 (3) ◽  
pp. 1526-1532 ◽  
Author(s):  
G. Naveen Kumar ◽  
R. Narayanasamy ◽  
S. Natarajan ◽  
S.P. Kumaresh Babu ◽  
K. Sivaprasad ◽  
...  
Keyword(s):  
Sliding Wear ◽  
Room Temperature ◽  
Wear Behaviour ◽  
Dry Sliding Wear ◽  
Dry Sliding ◽  
In Situ Composite ◽  
Sliding Wear Behaviour

Halo formation in directionally solidified Al2O3-Er3Al5O12 off-eutectic in situ composite ceramics

2019 ◽  
Vol 150 ◽  
pp. 31-37 ◽  
Author(s):  
Qun Ren ◽  
Haijun Su ◽  
Jun Zhang ◽  
Guangrao Fan ◽  
Haifang Liu ◽  
...  
Keyword(s):  
Composite Ceramics ◽  
Directionally Solidified ◽  
Halo Formation ◽  
In Situ Composite

Tensile and Creep Properties of the Refractory Nb Base In-Situ Composite

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1608-1614
Author(s):  
Jin Hak Kim ◽  
Tatsuo Tabaru ◽  
Hisatoshi Hirai
Keyword(s):  
Fracture Surface ◽  
Tensile Tests ◽  
Constant Load ◽  
Tensile Creep ◽  
Tensile Fracture ◽  
Creep Tests ◽  
Tensile Fracture Surface ◽  
In Situ Composite ◽  
Temperature Ranges

Niobium-base in-situ composite Nb-18Si-5Mo-5Hf-2C (in mol%) was prepared and heat-treated at 2070 K for 20 hour. The uni-axile tensile tests at high temperature ranges and the constant load tensile creep tests at 1570 K were performed. The specimen tensile-tested at 1470 K exhibited the excellent UTS of 450 MPa, and the brittle to ductile transition temperature is between 1470 and 1670 K. The specimens creep tested showed good creep strength; the stress exponent is about 5. The tensile fracture surface of the in-situ composite is complex and attributed to cleavage of the Nb 5 Si 3, Nb ss / Nb 5 Si 3 interface separation, ductile rupture of the Nb ss and correlations of these. On the otherhand, the fracture surface of creep tested consists of intergranular above 150 MPa and transgranular below 120 MPa with severely deformed Nb ss .

Solidification microstructure of laser floating zone remelted Al2O3/YAG eutectic in situ composite

2012 ◽  
Vol 345 (1) ◽  
pp. 51-55 ◽  
Author(s):  
K. Song ◽  
J. Zhang ◽  
X.J. Jia ◽  
H.J. Su ◽  
L. Liu ◽  
...  
Keyword(s):  
Solidification Microstructure ◽  
Floating Zone ◽  
In Situ Composite
Sign in / Sign up

Export Citation Format

Share Document