Key To Steel 2010 Free Download
As mentioned earlier, casting process of implant alloy is relatively more difficult than TMP of wrought alloys. The reason is due to the high reactivity of the alloys, especially for the case of Ti alloys, which easily reacts with both the atmosphere and the cast mold (Campbel, 2006). However recent progress shows the used of investment casting has increased which is followed with hot iso-static pressing (HIP) process as the primary process for the production of implant alloys. In addition, different with other alloys, cast products of Ti alloys are generally comparable with the wrought products and in certain case can be superior (ASM, 1998a). On the other hand, Co base alloys are considered to have a better cast-ability than both Ti and stainless steel alloys. These alloys shows several important characteristics for casting process such as good fluidity, low melting points, freedom from dissolved-gas defects and low alloy losses due to oxidation (ASM, 1998c). Improvement of cast-ability and cast product of this alloy can be achieved by additional alloying element such as carbon and vacuum melting process. It was reported that additional carbon content up to 0.5wt% lower the melting temperature (increase cast-ability) and in turn produce finer grain size as compared to binary CoCr alloys (Black, 1998).
key to steel 2010 free download
Stainless steels for metal implants have been further developed to be Ni-free. Replacing Ni with other alloying elements while maintaining the stability of austenitic phase, corrosion resistance, magnetism and workability, has lead to the use of nitrogen creating FeCrN, FeCrMoN and FeCrMnMoN systems. The high strength which has been achieved opens the possibility for reduction of implant sizes where limited anatomical space is often an issue, for example, coronary stents with ﬁner meshes (Yang, 2010).
Metallic glasses are novel class of metals which currently gets attention from biomaterialist (Schroers, 2009). As represented by some Ni-free Zr based bulk metallic glasses, they show interesting properties in term of higher tensile strength, lower elastic modulus and higher corrosion resistant compared to those of crystalline alloys (Chen, 2010). 350c69d7ab