A sintered body of TiB2-reinforced iron matrix composite (Fe-TiB2) is fabricated by pressureless-sintering of a mixture of titanium hydride (TiH2) and iron boride (FeB) powders. The powder mixture is prepared in a planetary ball-mill at 700 rpm for 3 h and then pressurelessly sintered at 1300, 1350 and 1400oC for 0-2 h. The optimal sintering temperature for high densities (above 95% relative density) is between 1350 and 1400oC, where the holding time can be varied from 0.25 to 2 h. A maximum relative density of 96.0% is obtained from the (FeB+TiH2) powder compacts sintered at 1400oC for 2 h. Sintered compacts have two main phases of Fe and TiB2 along with traces of TiB, which seems to be formed through the reaction of TiB2 formed at lower temperatures during the heating stage with the excess Ti that is intentionally added to complete the reaction for TiB2 formation. Nearly fully densified sintered compacts show a homogeneous microstructure composed of fine TiB2 particulates with submicron sizes and an Fe-matrix. A maximum hardness of 71.2 HRC is obtained from the specimen sintered at 1400oC for 0.5 h, which is nearly equivalent to the HRC of conventional WC-Co hardmetals containing 20 wt% Co.

TiB2-reinforced iron matrix composite (Fe-TiB2) powder was in-situ fabricated from titanium hydride (TiH2) and iron boride (FeB) powders by the mechanical activation and a subsequent reaction. Phase formation of the composite powder was identified by X-ray diffraction (XRD). The morphology and phase composition were observed and measured by field emission-scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS), respectively. The results showed that TiB2 particles formed in nanoscale were uniformly distributed in Fe matrix. Fe2B phase existed due to an incomplete reaction of Ti and FeB. Effect of milling process and synthesis temperature on the formation of composite were discussed.

The present study was focused on the synthesis of a dispersed copper matrix composite material by the combination of the mechanical milling and plasma activated sintering processes. The mixed powder was prepared by the combination of the mechanical milling and reduction processes using the copper oxide and titanium diboride powder as the raw material. The synthesized mixed powder was sintered by the plasma activated sintering process. The hardness and electric conductivity of the sintered bodies were measured using micro vickers hardness and four probe method, respectively. The relative density of composite material sintered at showed about 98% of theoretical density. The composite material has a hardness of about 130Hv and an electric conductivity of about 85% IACS. The hardness and electric conductivity of composite material were about 140 Hv and about 45% IACS, respectively.

Dispersion-strengthened copper with was produced by ball-milling and spark plasma sintering (SPS).Ball-milling was performed at a rotation speed of 300rpm for 30 and 60min in Ar atmosphere by using a planetary ball mill (AGO-2). Spark-plasma sintering was carried out at for 5min under vacuum after mechanical alloying. The hardness of the specimens sintered using powder ball milled for 60min at 300rpm increased from 16.0 to 61.8 HRB than that of specimen using powder mixed with a turbular mixer, while the electrical conductivity varied from 93.40% to 83.34%IACS. In the case of milled powder, hardness increased as milling time increased, while the electrical conductivity decreased. On the other hand, hardness decreased with increasing sintering temperature, but the electrical conductiviey increased slightly

TiC-TiB2-SiC system was a ternary eutectic, whose eutectic composition was 34TiC-22TiB2-44SiC (mol%). TiC-TiB2-SiC ternary eutectic composite were synthesized by a floating zone method using TiC, TiB2 and SiC powders as starting materials. The TiC-TiB2-SiC eutectic composite showed a lamellar texture. TiC(022), TiB2(010) and SiC(111) of the eutectic composite were perpendicular to the growth direction. TiC-TiB2-SiC ternary eutectic composite had specific relationship among the crystal planes: TiC[011]//TiB2[010]//SiC[112], TiC(200)//TiB2(001)//SiC( 402 ) and TiC( 111 )//TiB2(101 )//SiC( 220 ).

Nanostructured and composite powders have been prepared by mechanochemical reaction from mixtures of Ti, BN, and powders. The raw materials have reacted to form a uniform mixture of TiN, and or depending on the amount of used in the starting mixtures, and the reaction proceeded through so-called mechanically activated self-sustaining reaction (MSR). Fine TiN and crystallites less than a few tens of nanometer were homogeneously dispersed in the amorphous or matrix after milling for 12 hours. These amorphous matrices became crystalline phases after annealing at high temperatures as expected, but the original microstructure did not change significantly

Nano-sized was in situ synthesized in copper matrix through self-propagating high temperature synthesis (SHS) with high-energy ball milled Ti-B-Cu elemental mixtures as powder precursors. The size of particles in the product of SHS reaction decreases with time of preliminary mechanical treatment ranging from 1 in untreated mixture to 0.1 in mixtures milled for 3 min. Subsequent mechanical treatment of the product of SHS reaction allowed the particles to be reduced down to 30-50 nm. Microstructural change of -Cu nanocomposite during spark plasma sintering (SPS) was also investigated. Under simultaneous action of pressure, temperature and electric current, titanium diboride nanoparticles distributed in copper matrix move, agglomerate and form a interpenetrating phase composite with a fine-grained skeleton.

Interpenetrating phase composites of -Cu system were produced via Spark-Plasma Sintering (SPS) oi nanocomposite powders. Under simultaneous action of pressure, temperature and electric current titanium diboride nanoparticles distributed in copper matrix move, agglomerate and form a fine-grained skeleton. Increasing SPS-temperature and he]ding time promote densification due to local melting of copper matrix When copper melting is avoided the compacts contain 17-20% porosity but titanium diboride skeleton is still formed representing the feature of SPS . High degree of densification and formation of titanium diboride network result in increased hardness of high-temperature SPS-compacts.

The effects of boron or manganese added as , Mn, , B on TiC-30vo1.% cermet sintered at 1380 and for 1 hour, were examined in relation with shrinkage, relative density, microstructure, lattice parameter, hardness and fracture toughness (). The results are summarized as follows: 1) The highest shrink-age showed about 30.5% in the specimen added BC and the maximum relative density was about 99% in the specimen added ; 2) The grains of TiC were grown during sintering and made the surrounding structure by adding boron and manganese. The largest grain size showed about in the specimen with boron sintered at ;3) The lattice parameter of TiC was about and about by adding other elements; 4) The highest hardness was about in the specimen with B4C; 5) The fracture toughness () showed about in the specimen added .

기계적합금법으로 Ti와 B의 혼합분말로부터 TiB2분말을 제조하였고, Zr과 Ta의 Ti 치환 효과를 조사하였다. (Ti+B)의 혼합분말을 280시간 분쇄하여 TiB2단일상을 얻었고 기계적합금화 도중 비정질상은 관찰되지 않았다. Ti의 일부를 원자반경이 Ti보다 큰 Zr으로 치환한 결과 기계적합금화에 걸리는 시간이 크게 감소한 반면에, 붕화물 생성열이 절대값이 TiB2상보다 작은 Ta로 치환하면 280시간 분쇄하여도 단일상을 형성하지 못하였다.