Abstract
Transient liquid phase (TLP) bonding can be used for joining advanced materials containing secondary strengthening phases, with the advantage of producing isothermally solidified joints, free from precipitates and defects. However, this study shows that when TLP bonding an oxide dispersion strengthened alloy MA957, initial melting and homogenisation of the liquidfiller metal results in parent metal dissolution and the loss of any dispersion strengthening phases from the joint region. A theoretical study shows that the extent of dissolution is determined by the thickness of the inter layer used, and it is suggested that thinner interlayers in the form of sputter coatings will reduce dissolution significantly. Experimental results show that 2 μm thick sputter coatings based on the Fe-B-Si ternary system can be deposited by rf sputtering techniques. The TLP bonds produced are free from intermetallic precipitates and pores and show no agglomeration of the dispersion strengthened phase, and this is attributed to the lower volume of boron and silicon deposited in the coatings.
MST/3454
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