Dawei Yi

Effect of Titanium and Nitrogen Additions on the Microstructures and Three-Body Abrasive Wear Behaviors of Fe–B Cast Alloys

This study investigates the effect of titanium and nitrogen elements on the microstructures and wear behaviors of medium carbon Fe–B cast alloy. The as-cast microstructures of Fe–B cast alloy consist of the eutectic boride, pearlite, and ferrite. Moreover, the as-cast eutectic boride structures are greatly refined when titanium and nitrogen are added. The boride area fraction, average boride area, Rockwell hardness, etc., are also investigated systemically. The wear behaviors of medium carbon Fe–B cast alloy are studied by a three-body abrasive wear tester. The results show that the wear weight loss of Fe–B cast alloy with titanium and nitrogen elements is lower than that of the ordinary Fe–B cast alloy. Meanwhile, the wear mechanism of Fe–B cast alloy with different titanium and nitrogen concentrations is described and analyzed.

Investigations on Microstructures and Three-Body Abrasive Wear Behaviors of Fe–B Cast Alloy Containing Cerium

AbstractnThe effect of the element cerium on the microstructure and wear behavior of Fe–B cast alloy was investigated by scanning electron microscope, transmission electron microscope, X-ray diffraction analysis, Leica digital image analysis, hardness tester and abrasion tester. The microstructures of as-cast Fe–B alloy are composed of the phase ferrite, pearlite and eutectic boride. Moreover, the as-cast eutectic boride structures in Fe–B alloy containing cerium are finer than that in the alloy having no cerium. After heat treatment, the average boride area and wear weight loss of the alloy containing cerium are lower than these of the alloy having no cerium. Before the formation of primary austenite, cerium can combine with oxygen to form Ce2O3. Ce2O3 can act as nuclei of primary austenite, promoting the refinement of austenite and borides during solidification, and improve the wear property of Fe–B alloy.

Interface Structure and Wear Behavior of Cr26 Ferrous Matrix Surface Composites Reinforced with CTCP

Using cast tungsten carbide particles (CTCP) and reduced iron powders as raw materials, the porous ceramic preforms with honeycomb, strip, and layer structure, respectively, were prepared by loose sintering process; then, the CTCP/Cr26 ferrous matrix composites were fabricated by casting infiltration process. The microstructure of the composites was analyzed by SEM, XRD, and EDS. The results show that a sintered shell forms as a result of the reaction of Fe and W2C in the CTCP during loose sintering process; the inner part of the shell around the CTCp consists of WC and Fe3W3C phases, while the outer part between the particles is dominated by Fe3W3C. Therefore, the strength of preforms is enhanced because the particles are connected with each other by sintered shell. During casting infiltration process, a transition layer constituted by WC and Fe3W3C formed at the interface of CTCp and the matrix due to the dissolution and precipitation of the sintered shell in the high-temperature liquid iron. The three-body abrasive wear behavior of the composites was investigated. The result shows the wear resistance of honeycomb structure composite is comparable to that of whole layer (WL) structure composite, which is three times of heat-treated Cr26. However, the honeycomb structure composite has higher performance/cost ratio owing to the lower CTCp volume fraction and higher strength and toughness compared with the WL structure composite.

Structural, bonding, anisotropic mechanical and thermal properties of Al4SiC4 and Al4Si2C5 by first-principles investigations

Abstract The structural, bonding, electronic, mechanical and thermal properties of ternary aluminum silicon carbides Al4SiC4 and Al4Si2C5 are investigated by first-principles calculations combined with the Debye quasi-harmonic approximation. All the calculated mechanical constants like bulk, shear and Young’s modulus are in good agreement with experimental values. Both compounds show distinct anisotropic elastic properties along different crystalline directions, and the intrinsic brittleness of both compounds is also confirmed. The elastic anisotropy of both aluminum silicon carbides originates from their bonding structures. The calculated band gap is obtained as 1.12 and 1.04 eV for Al4SiC4 and Al4Si2C5 respectively. From the total electron density distribution map, the obvious covalent bonds exist between Al and C atoms. A distinct electron density deficiency sits between Al–C bond along c axis among Al4SiC4, which leads to its limited tensile strength. Meanwhile, the anisotropy of acoustic velocities for both compounds is also calculated and discussed.

Investigations on Microstructures and Toughness of Fe-B Cast Alloy Containing Titanium and Nitrogen

The effects of titanium and nitrogen elements on the microstructure and impact toughness of the Fe-B alloy have been studied. The results show that the borides are refined after the additions of titanium and nitrogen elements. With the additions of titanium and nitrogen, titanium nitrides are formed in the Fe-B alloy. Titanium nitride can act as effective heterogeneous nuclei of primary austenite, and promote the refinement of austenite and boride. After heat treatment, the impact toughness of Fe-B alloys modified by titanium and nitrogen elements is higher than that of ordinary alloy.

A study on the microstructures and three–body abrasive wear behaviors of Fe–B alloy under different Fe2B boride orientation

Purpose n n n n nThe directional solidification Fe-B alloy was prepared. The microstructures and three-body abrasive wear behaviors of directional solidification alloy were investigated. n n n n nDesign/methodology/approach n n n n nFe-B alloy was melted in medium frequency induction furnace. The hardness was measured on HRS-150 Rockwell-hardness tester and HXD-1000TMC tester. The wear characteristic of the alloy was examined with a block-on-ring geometry. The worn surface of the alloy was investigated by scanning electron microscopy and laser scanning microscopy. n n n n nFindings n n n n nThe wear weight loss and worn surface roughness increase with the increasing contact load in wear tests. When the worn surface is perpendicular to the boride growth direction, the highest hardness plane of the boride can resist abrasive effectively under the surrounding and supporting of the martensite matrix. n n n n nOriginality/value n n n n nThe relation between boride growth direction and wear direction will cause different boride breaking tendency and wear weight loss.

A Study on the Microstructures and Toughness of Fe-B Cast Alloy Containing Rare Earth

AbstractnThis study investigates the effect of cerium on the microstructures, mechanical properties of medium carbon Fe-B cast alloy. The as-cast microstructure of Fe-B cast alloy consists of the eutectic boride, pearlite, and ferrite. Compared with the coarse eutectic borides in the unmodified alloy, the eutectic boride structures in the modified alloy are greatly refined. Cerium promotes the formation of Ce2O3 phase. Ce2O3 can act as effective heterogeneous nuclei of primary austenite, and refine austenite and boride. After heat treatment, the impact toughness of the modified alloy is higher than that of the unmodified alloy because there are more broken borides in the modified alloy. Meanwhile, the fracture mechanism of medium carbon Fe-B alloy is depicted and analyzed by using fractography.