The effect of ADI heat treatment conditions on the core microstructures and mechanical properties of GCD 45 has been investigated. In the case of $25{\ss}{\AE}$ in diameter, it has been found that pearlite structure is not obtained, and the matrix is consisted of graphite, bainite and retained austenite. Upon cooling isothermally from $900^{\circ}C$, the core structure of 35 mm in diameter is converted to pearlite. However, the structure is transformed to bainite after slow cooling from $900^{\circ}C$ to $800^{\circ}C$.

Deformation behavior of nickel-rich Ti-51.5at.%Ni single crystals was investigated over a wide range of temperatures(77 to 440K) and strain levels(up to 9%) in compression. These alloys combined superior strength with wide range of pseudoelasticity temperature interval(~200K). The slip deformation in [001] orientation did not occur due to the prevailing slip system, and consequently, exhibited pseudoelastic deformation at temperatures ranging from 77 to 283K and 273 to 440K for the solutionized and over-aged cases, respectively. The critical transformation stress levels were in the range of 800 to 1800MPa for the solutionized case, and 200 to 1000MPa for the over-aged case depending on the temperature and specimen orientation. These stress levels are considerably higher compared to these class of alloys having lower Ni contents. The maximum transformation strains, measured from incremental straining experiments in compression, were lower compared to the phenomenological theory with Type II twinning. A compound twinning model depending on the successive austenite(B2) to intermediate phase(R) to martensite(B19') transformation predicts lower transformation strains compared to the Type II twinning case.

In conventional metallothermic reduction(MR) for obtaining tantalum powder in batch-type operation, it is difficult to control morphology and location of deposits because the reaction occurs by direct physical contact between reductants and feed materials. On the other hand, a electronically mediated reaction(EMR) is capable to overcome these difficulties through the reaction by electron transfer and have a merit of continuous process. In this study an MR and EMR method has been applied to the production of a tantalum powder by sodium reduction of $K_2TaF_7$. As the reduction temperature increases, the particle size and yield of tantalum powder obtained by MR and EMR method is increased.

The electrode materials for welding machine in automobile industry such as Cu-Cr, Cu-Zr and Cu-$Al_2O_3$ require the high electrical conductivity and the proper hardness. Therefore the effects of solution heat treatment and aging treatment on the electrical conductivity and hardness of Cu-0.8wt%Cr and Cu-1.2wt%Cr alloys have been investigated. Cu-0.8wt%Cr alloy showed the higher electrical conductivity and hardness than Cu-1.2wt%Cr alloy and both alloys showed the better electrical conductivity at $930^{\circ}C$ among 930, 980 and $1030^{\circ}C$ solution heat treatment temperatures. The electrical conductivity and hardness in both alloys were not affected by aging treatment but remarkably affected by solution heat treatment temperature. The final drawing process reduced electrical conductivity and increased hardness more in Cu-1.2wt%Cr alloy.

그동안 열처리기술 경기대회는 열처리공업 협동조합의 주관으로 치루어졌었는데, 올해에는 처음으로 한국열처리공학회에서 주관하여 치루게 되었다. 경기종목과 경기요령은 기존의 방법을 거의 그대로 사용하였고, 평가항목과 심사기준도 일부 변경하기는 하였지만 대부분 그대로 적용하였다. 경기종목 선정과 분석결과에 대하여 일부 논란이 있었지만 현실적으로 주어진 여건하에서 국내 열처리업체의 기술수준을 평가할 종목선정에 제한적일 수 밖에 없었으나, 앞으로 새로운 종목의 발굴도 필요하리라 사료된다. 또한 평가항목의 심사기준도 좀더 면밀히 검토하여 업체의 기술수준이 드러나도록 심사기준의 설정이 요구된다. 비록 완전하게 치루어진 경기대회라고 평가할 수는 없지만 그래도 객관적이고도 공평한 분석으로 평가가 이루어지도록 노력하였고, 차후로는 더욱 섬세하고 객관적인 평가항목으로 공정한 평가가 이루어지도록 배전의 노력을 기울여야 할 것으로 사료된다. 끝으로 이러한 열처리기술 경기대회를 통하여 국내열처리업계의 기술수준이 조금이나마 제고되는 기회가 되길 바라며, 열처리업계의 적극적인 참여를 바라마지 않는다.