a thermal processing chamber configured to be maintained at approximately atmospheric pressure;

a workpiece support configured to support a workpiece in the thermal processing chamber during a thermal process;

one or more heat sources configured to heat the workpiece during the thermal process; and a gas supply comprising:

a first gas line configured to admit a forming gas into the thermal processing chamber at a first flow rate, the forming gas comprising a mixture of an inert gas and a hydrogen gas, a concentration of the hydrogen gas in the mixture being less than about 4% by volume;

wherein the first flow rate is such that a partial pressure of the hydrogen gas in the thermal processing chamber is less than about 10 Torr, and the workpiece is exposed to the forming gas at approximately atmospheric pressure;

wherein the gas supply further comprises a second gas line configured to admit an oxygen gas into the thermal processing chamber at a second flow rate, wherein the workpiece is exposed to the oxygen gas in the thermal processing chamber at approximately atmospheric pressure while the one or more heat sources heat the workpiece such that the forming gas and the oxygen gas at least partially oxidize a portion of the workpiece; and

wherein the second flow rate is such that a partial pressure of the oxygen gas in the thermal process chamber is in a range of about 30 Torr to about 50 Torr.